The Intern

Variant form of Naive Newcomer. The young guy (often the Plucky Comic Relief) who is still new to the whole place. He's often brilliant, almost always irreverent, and almost always "not ready for prime time" (i.e. throwing up the first time he sees a serious accident, etc).

Often, it's clear that The Intern was a former Teen Genius, but is now learning that life is much tougher in the field.

Comics

 * Comic strip example: Asok of Dilbert.

Film

 * The Life Aquatic With Steve Zissou had a group of college interns whom the titular character (and to some extent the rest of the crew) treats like crap: Steve refers to each as "intern!" rather than by name, forces them to loot an underwater research station owned by his rival and when they quit after the ship was briefly taken over by pirates, he sends them all home with "Incomplete" in their evaluations (his reason being that he didn't want to fail them, but he didn't want them to pass either).
 * One of them, however, decided to stick around. Zissou immediately promised him an "A".

Literature

 * Uli Divini in the Medstar Duology, although by Death Star he was much older and more experienced.

Live Action TV

 * John Carter (Noah Wyle) on ER
 * Which lead to the really cool Character Development of John Carter from The Intern to The Veteran, followed by him handing off his title to the next in line, much as Dr. Green had done to him, when he left the show. Of course, it took ten years...
 * Greg the Lab Rat on CSI
 * Dr. Bashir in the first few seasons of Star Trek: Deep Space Nine
 * The entire premise, especially in the first season, of Scrubs.
 * Which comes full circle as JD, Turk, and Elliot, who were the first batch of interns in season 1, become residents and then attendings, acquire their own interns, and eventually wind up as senior staff by season 8 and are now in the role of mentors.
 * In the first season of The Muppet Show, Scooter is cast as an inexperienced newbie whom Kermit was forced to hire as a gofer because his uncle owned the theater. Several early episodes feature Scooter coming to Kermit with ridiculous "fresh new ideas" for the show that Kermit puts into action against his will for fear of losing his lease. As the show went on, Scooter's antagonistic side was dropped and his uncle was barely ever mentioned.
 * Calum Buchanan in All Creatures Great and Small.
 * McGee was like this during his first season on NCIS, and Tony still taunts him for being this trope.
 * Meredith, Christina, Alex, Issy and George were all this character for the first three seasons of Grey's Anatomy.
 * Kenneth
 * The main cast of the Russian sitcom The Interns.
 * Yuki in Casualty, and to a lesser extent, Lenny. A few seasons earlier, Toby fit the role pretty well.
 * Zach on Bones, at first. When his internship ends, the team keeps him on. After he leaves the show, he's replaced by a rotating roster of interns.

Western Animation

 * Major Monogram's assistant Carl, from Phineas and Ferb.
 * Billy from Total Drama Island.