Fictional Sport

The sport equivalent to the Fake Band: A "real" sport invented for the work itself which is played in the 'verse of the work, with clear rules that could actually be followed if the sport were real (that is, not Calvin Ball). Can become Defictionalized if someone manages to create feasible real-life rules for the game. This is somewhat limited by what type of universe it exists in. If its one that's made up, but still follows real laws of physics (eg. a fake card game), no problem. However, if it uses advanced technology or magic, its a bit hard to recreate. That said, you'll be amazed how creative fans can be.

Sometimes a Blood Sport.

Comic Books

 * Legion of Super Heroes has magnoball (both Cosmic Boy and his brother are former champions).

Film

 * Rollerball.
 * Baseketball.
 * Jugging, from the film The Blood Of Heroes, actually inspired fans in Germany to play the sport for real.

Literature

 * Harry Potter: Quidditch, natch.
 * Defictionalized as Muggle Quidditch. One of the ways of getting around the fantastical elements of the sport is that the Snitch is a neutral party that runs around not just the field but also (or at least in college games) all over campus as well.
 * In Artemis Fowl, zero-G and garbage wrestling are mentioned.
 * Young trainees at the Assassins' Guild engage in the Discworld sport of edificeering, which is competitive free-climbing in an urban environment. Possibly inspired by Le Parkour.
 * Scavage and Counterchance in the Liaden Universe. Bowli ball might also apply, but it's more like a (literal) Happy Fun Ball.
 * The live-action Games from the Dream Park series could probably be staged today, if low-tech alternatives to holographic enemies could be adopted: it'd just be insanely expensive. A low-tech version of the Crystal Maze from The California Voodoo Game could likewise be produced, given a massive budget for construction and design.

Live Action TV

 * Star Trek has 3-D chess. What? Chess is a mind sport!
 * In later series has characters playing Parrises Squares in the holodeck.
 * Pyramid and Triad in Battlestar Galactica.
 * A 2nd series episode of Look Around You had a feature on gonnis (golf tennis).
 * An episode of the Finnish sketch show Kummeli had a sketch on Tamping, a fictional sport where the participant must travel the world and cover every square inch of the world with his own clown-shoe footprints - that is, to step on absolutely everything in the world. The sketch also served as a vehicle for puns related to feminine hygiene products: The sketch mentions one man who has tamped the entire world three times: Kenji Nakami, also known as the Tampon, and one square acre of tampable territory is known as a Tampax.

Tabletop Games

 * The Shadowrun supplement Shadowbeat includes full descriptions of the new Sixth World sports of Combat Biker and Urban Brawl, as well as information about how cyberware has revolutionized boxing, baseball, basketball, and (especially!) American football.
 * Alphatians in the Mystara D&D setting are big-time fans of a team sport called hardball, which is played on a court divided into squares and involves a lot of complicated passing between players.

Video Games

 * Final Fantasy X: Blitzball.
 * Not to be confused with another sport also called Blitzball, as seen in Knowles' A Separate Peace.
 * Neopets gives us the Altador Cup and Gormball.
 * Star Control: Frungy, frungy, frungy!

Webcomics

 * Smackball, a new sport mentioned in the Distant Finale of the webcomic Penny and Aggie. Writer T Campbell described it in the comic's forum as a cross between jai alai and tennis.
 * Boxer Hockey in the web comic of the same name. The rules are given in the first strip it would be possible but extremely dangerous to play in real life.
 * Mac Hall: Australian Indoor Rules Quidditch.

Western Animation

 * Futurama has Blernsball. There are actually two episodes centered around it, and it changes almost completely between viewings. The first time, Fry looks like an idiot for using baseball terminology, but the second, it's almost identical to baseball.
 * The Legend of Korra brings us "Pro-Bending". Teams composed of one water-bender, one fire-bender and one earth-bender compete against each other, trying to gain the most territory or knock out as many opponents as possible before time runs out.
 * Dinoball in Dinosaur Train.

Other

 * Bionicle has Kolhii -- a cross between hockey and lacrosse that can be played with two or three teams. Also Ailini, played by throwing disks through hoops, while simultaneously sliding on disks on a shifting field.
 * Red vs. Blue: Grifball, which became so popular, less than three years after its inception, it was the only sport played.

Real Life?

 * Real Life example (in that it could be played, it's just too complicated and dangerous today) that shows up in some french Historical Fiction: "Soule", a kind of cross-country/inter-village wrestling meet/capture the flag/rugby match where the goal is to get a pig's bladder from one village to another, with the opposing villagers trying to stop the others. Chaos guaranteed, bone fractures not uncommon, Hilarity Ensues. It almost always seems better than it sounds, too...
 * Medieval England (and later centuries) had some fairly gruesome sports no longer played for safety reasons. Peasant jousting involved two people skating towards each other on ice and trying to knock each other down with a stick, which often resulted in severe injuries or death. Early soccer/football was played between entire towns, and the goal was to kick an inflated pig's bladder between the gates of the other town's cemetery; there were no rules and serious injuries or deaths were common.