Career-Ending Injury

I used to be an adventurer like you. Then I took an arrow in the knee.

—Guards from The Elder Scrolls V: Skyrim

A Career-Ending Injury is a sudden and unexpected injury or illness that causes a disability to a person and forces them to give up their ambitions and dreams.

Usually this trope involves an athlete getting an injury, but the career can be anything that requires physical and/or mental ability. Likewise, what causes the disability can be something other than an injury (for example, a disease) -- the important point is that it prevents the character from achieving their goals by causing a disability.

A variation is where a previously known condition or illness worsens unexpectedly to a point where the character is no longer fit for his/her career.

Sometimes the injury is part of the backstory, but if it happens during the course of the main story, expect Angst.

Very much a Truth in Television.

Compare White Dwarf Starlet and I Coulda Been a Contender, common results of this trope, and Sorry, Billy, But You Just Don't Have Legs, where the character is disabled to start with instead of becoming so during their career. If the character overcomes the injury, either temporarily or permanently, then they're Back in the Saddle.

This is sometimes set up as a twist or a reveal, so beware of spoilers.

Examples of Career-Ending Injury include:

Anime and Manga

Sometimes Hero Killer Stain, from My Hero Academia opts to inflict this upon his targets instead of killing them.
In The Animatrix short "World Record", a sprint runner almost exits the Matrix during the record-breaking sprint but is pulled back inside, where his mind decides he has ran past his body capacities and breaks said body. He is left in a wheelchair for the rest of his life.
In Battle Angel Alita, Alita's motorball trainer used to be a racer but had to retire after overuse of reflex-boosting drugs damaged his nervous system. Subverted for Jasugun who knows his brain is dying from being tampered with too much but chooses to die on the track as a champion.
Rideback: Rin gives up being a ballerina due to physical (and mental) injuries caused by a fall.
In Berserk, Gutts' foster father has to retire as an active mercenary after a messy leg injury. Averted for Gutts himself - you would think that losing a hand would end the career of a fighter who specialises in two-handed weapons, but he is stubborn enough to learn to handle the sword using prosthetic hand. (A magnet in the hand helps him maintain the grip.)
Gerd in Blassreiter was a racing champion who got half-paralyzed. And then ditched by his girlfriend. And then agreed to try an "experimental healing".
When the manga H 2 begins, baseball players Hiro and Noda both believe they've suffered such injuries. Hiro to his arm, Noda to his back. They soon discover, though, that their supposedly great doctor was unlicensed and they are, in fact, perfectly healthy.
Almost happens to Hayato and Randoll in Future GPX Cyber Formula in the ZERO arc when they suffered serious injuries in a crash at the British GP. They got better and they return to racing (although Randoll takes longer to come back than Hayato).
- In Bootsvorz's backstory, a nasty crash at a test drive resulted in losing his left eye and arm, but he returned to racing after gaining a new arm and eye.
- Johji Ohtomo quits CF racing after a crash at the German GP that was indirectly caused by Hayato's Super Asurada 01 crashing into Ohtomo's car and he suffers serious injuries as a result.
- A racer named John Cleeve has his racing career ended when a car accident, but it happened outside the race track.
In Hajime no Ippo, Nekota was forced to give up boxing after an illegal punch from his opponent resulted in permanent mid-brain damage and punch-drunk syndrome, although he experienced the symptoms of the latter before the fight (it was from a fight with his friendly rival).
In the Case Closed Non-Serial Movie The Fourteenth Target, the murderer is revealed to be a sommelier whose taste buds were destroyed in an accident, taking revenge on the people who ended his career.

Comic Books

Stephen Strange was a gifted surgeon who lost the dexterity in his hands in a car accident. His quest for a cure eventually led him to the Ancient One, who taught him the mystic arts.

Film

Sebastian in The Greatest Show on Earth ends his career as a trapeze artist from performing a dangerous trick.
Subverted in Unbreakable. The titular character supposedly had an injury that made it impossible for him to continue playing football, but he faked it because, he's the title character.
Halfway through Cars, Lightning discovers that Doc Hudson was actually the Fabulous Hudson Hornet, a legendary racecar. Doc ultimately explains that the only reason he "quit" racing was because he suffered a major crash during a race. By the time he could race again, the racing industry merely brushed him off without a second thought.
Million Dollar Baby has a very heart-wrenching one of these near the end of the movie. A nasty cheap shot from behind results in Maggie's neck being broken when she lands on a corner stool, resulting in her being paralyzed from the neck down. As boxing was her passion and her life and she will never be able to fight again, Maggie wants to die, and her mentor ultimately makes the decision to give her an assisted suicide.
The Rookie (which is Based on a True Story) is about a baseball player trying to come back after a supposed one of these. He made it to the major leagues... then suffered the same injury again, over ten years after the initial injury.
Remember the Titans has the automobile accident that ends the football career of star linebacker Gerry Bertier.
At the beginning of Shaolin Soccer the man who will become the coach to our heroes is a Jerkass soccer superstar until the teammate he's been lording it over hires people to cripple the star.
In Forrest Gump, Lieutenant Dan has to leave the army after losing his legs in Vietnam. He had an ancestor die in "every single American war" and believed the same was supposed to happen to him, so being left alive but unable to fight turns him into an alcoholic mess for a long time.
Gattaca: the guy whose DNA the protagonist is using used to be an athlete until an undisclosed incident confined him to a wheelchair.
Joe's knee injury in Bend It Like Beckham, which was caused by his father pushing him too hard.
Danny Glover's Jaded Washout character in Angels in the Outfield had his career cut short because the villainous sportscaster character deliberately slid into home with his spikes up when they were playing each other years before.
In the original timeline of Back to The Future, a car accident ends Marty's rock career before it even took off the ground.
In the live-action Teenage Mutant Ninja Turtles, Casey says he used to "play professionally until I got hurt". Presumably he means hockey.

Literature

A major plot point in A Separate Peace.
Happens several times in Warrior Cats. For the most part, the cat is already considerably old when it happens:
- Stonepelt retires early due to a shoulder injury that didn't heal properly.
- Longtail also retires early when he goes blind from infected scratched eyes.
- The most notable example in the series, though, is Cinderpelt, whose hind leg was permanently damaged when she was hit by a car when she was only an apprentice. She dreamed of being a warrior, but decided to serve her Clan as a medicine cat after it became clear her leg would never heal.
In The Curious Case of Benjamin Button, Daisy is forced to retire as a ballet dancer after a hit by a cab breaks her leg.
A Song of Ice and Fire:
- Bran gets pushed out of a window and is paralyzed from the waist down, destroying any possibility of his ever being a knight.
- Willas Tyrell, the heir to Highgarden, was a promising knight until his leg got crushed in a tournament.
Johnny Tremain burns his hand early in the story, meaning he can't be a silversmith.

Live-Action TV

A plot point of Danny Messer's backstory in CSI: NY. He was an aspiring baseball player, but an arm injury forced him to quit. (a storyline incidentally drawn from the actor's real life background).
JAG is centered on a Navy aviator named Harmon Rabb. He was a career fighter pilot, following in his father's footsteps, until he crashed his plane in a night landing on an aircraft carrier due to an undiagnosed vision problem. In order to stay in the Navy, he went to law school and became an attorney with the Navy Judge Advocate General.
Space: Above and Beyond has Lieutenant Colonel T.C. McQueen, who was an elite fighter pilot before he suffered a debilitating head injury in combat. He has enough experience to warrant making him a squadron commander, acting in the role of Mission Control for his young pilots.
White Collar's Peter Burke was a professional baseball player when he tore his rotator cuff. The injury healed just fine and he was able to play baseball again, though a doctor advised him he could re-injure. Rather than risk losing both his baseball career and the possibility of joining the FBI, Peter opted to quit baseball and simply join the FBI.
It happens a couple of times on Mash. In one episode, a football player has to have his leg amputated. In another, a concert pianist loses dexterity in his hand.
In the pilot for Friday Night Lights Jason is paralyzed in an injury ending his planned career as a football player.
In an episode of Bones where the Victim of the Week is a professional motorcycle racer, one of the suspects is a parapalegic former racer who the victim had "accidentally" caused to crash in a previous race, causing the paraplegia.
In Blind Justice the protagonist is a police officer who is blinded due to an injury he sustains in the line of duty. This would normally end his career but he manages to subvert the trope by suing the police department to get his job back.
Tony Micelli of Who's The Boss? was a professional baseball player before a shoulder injury.
Monk was able to manage his OCD until his wife's death caused a breakdown that made the condition much worse. This ends his career as a police officer.
Frasier's dad Martin's bullet to the hip ended his police career.
Cheers established this as the reason Sam left baseball...with a twist.

Diane:So, why aren't you playing anymore?
Sam:I developed an elbow problem.
Diane:An elbow problem?
Sam:Yeah. Bent it too much.
Mimes drinking from a bottle.

Newspaper Comics

Lampooned in The Far Side, where one cartoon claims Albert Einstein played professional basketball before he hurt his ankle, and as a result, pursued a career in science.

Video Games

In The Elder Scrolls V: Skyrim, all guards share a pool of random sentences, which any of them can say. One of those is the page quote, making it sound like this is the backstory for every single guard.
Dead Island: the back story for Logan, an ex-football star.
Jagged Alliance 2 has an Alumni page on the AIM (Association of International Mercenaries) website, where among the retired, KIA and dishonorably discharged there are also those who suffered injury or had failing health.
In Resident Evil: The Darkside Chronicles this is revealed as the back story reason for why Krauser faked his death and defected to Wesker's side. Krauser used to be a special ops soldier who worked alongside Leon but during the course of the mission a viral entity impales his arm permanently crippling it. This was awful for Krauser because he liked his job in the U.S Military and wanted to continue it. Krauser eventually sought out Wesker who provided a way to heal his arm and out of gratitude now serves Wesker as his special agent, even got a sweet mutated arm blade out of the deal.
In Mass Effect 3, Thane's terminal illness known as Kepral's Syndrome finally reaches a point where Thane can no longer reliably perform his job as an assassin. However, this doesn't stop him from intervening to save the salarian Councilor when Kai Leng and Cerberus attacks, though the disease does slow him down to the point that he is badly wounded, and the injury itself will eventually kill him.
In Metal Gear Solid: Portable Ops this is given as the backstory for Lieutenant Cunningham of FOX, a CIA sponsored black ops organization, as he used to be a soldier during Vietnam but suffered an injury to his leg that required it to be amputated thus ending his career. During the story he expresses resentment towards the CIA for giving him a desk job after his injury when he used to be a distinguished warrior. A common theme in the overall story of the Metal Gear games is that soldiers are mistreated by their governments, Cunningham being downsized is viewed as another example of this ideal.

Western Animation

Kick Buttowski's mother Honey Splash ended her career as a speedboat stuntster because she tore her tendanacious ligamental flexor. Kick encourages her to try again years later, but the injury flares up at a plot appropriate moment.
Bruce from Batman Beyond gives up crime fighting due to a heart condition. On its own it probably wouldn't mean much, but the circumstances caused him to point a gun at someone.
Played for Laughs in the Veggie Tales story "Sumo of the Opera", where Mikey used to be in wrestling until he injured his knee. He's a grape.
Oban Star Racers: Rick Thunderbolt, the original earth team pilot, is seriously injured in his first race, leaving him with a nervous system that freezes up at inopportune moments. After some episodes moping about it he eventually agrees to help train Molly as his replacement.

Real Life

In one the most well-known examples from the NFL, Washington Redskins quarterback Joe Theismann was forced to retire after a Monday Night Football game in 1985. On a failed attempt to trick the New York Giants' defense, Theisman was sacked by all-pro linebacker Lawrence Taylor. As Taylor forced Theisman to the ground, his knee came down on Theisman's leg and snapped the tibia and fibula. While this incident helped cement Taylor's fearsome reputation, Taylor himself was clearly horrified and called for medical assistance for Theisman the moment he realized what had happened.
Lou Gehrig had to retire from baseball due to having amyotrophic lateral sclerosis (which became known as Lou Gehrig's disease.)
Nancy Kerrigan (figure skating): Her rival Tonya Harding hired someone to whack Kerrigan in the knee with a pipe, hoping to break her leg and take her out of competition for the Olympics. Didn't work. The incident with Kerrigan was parodied in the unreleased Data East-published Mortal Kombat clone Tattoo Assassins.
Monica Seles (tennis): Deranged fan of a rival runs onto the court during a match and stabs her in the back of the neck. She got better.
Edge was forced to retire from WWE fairly young due to injuries he'd sustained over his career.
- Professional Wrestling has plenty of these: Stone Cold Steve Austin retired after multiple neck injuries; Darren Drozdov became a quadriplegic due to a ring mishap, and then there are the injuries that weren't only career-ending, but life-ending.
Matt Smith originally wanted to be a professional footballer, but a back injury put an end to his early career. Considering he's now a world-famous actor and plays the lead character in one of the most popular TV shows in history (and even got to show off a little of his football chops in one episode), we're going to go out on a limb and presume he's not too bitter about it.
Despite winning via unanimous decision in a ten-round match against Luis Melendez of Colombia, Filipino boxer Z Gorres collapsed shortly after the verdict was announced, and was treated for haematoma, later undergoing extensive physical therapy for him to regain the ability to do day-to-day tasks. Said injuries have unfortunately spelled the end of his boxing career.