Superhero
A superhero was someone who protected other people from monsters and made them feel secure and safe. (PROSE: Forever Autumn) Some superheroes had secret identities and superpowers. (PROSE: Another Girl, Another Planet)
Several times people compared the Doctor to a superhero. Caroline Darnell thought that the Eighth Doctor was a superhero, and was disappointed when he told her that he wasn't. (PROSE: The Sleep of Reason)
Rick Pirelli had a similar feeling of security when he thought about the Tenth Doctor and superheros. To him the Doctor wasn't a superhero, but he was someone that he could turn to if the monsters showed up. (PROSE: Forever Autumn)
To Lucie Miller, the Eighth Doctor was like a superhero. (AUDIO: Death in Blackpool)
Galaxia was part of a trio of female superheroes that were created by Clyde Langer for one of his paintings. (TV: Mona Lisa's Revenge) Clyde Langer later drew the superhero Rocket Man. (TV: The Mark of the Berserker) Then Clyde created the superhero comic book The Silver Bullet. (TV: The Curse of Clyde Langer) In the comic book The Silver Bullet was a superhero that protected the city from crime. (COMIC: The Silver Bullet)
Iron Man was a fictional superhero. (PROSE: The Forgotten Army) Another fictional superhero was Karkus. He was the protagonist of a comic strip which appeared in the Hourly Telepress in the year 2000. (TV: The Mind Robber) The fictional superhero Superman crash-landed on Earth as a baby and was the last of his kind. (AUDIO: 1963: Fanfare for the Common Men) Batman was a fictional superhero that Clyde Langer admired. (TV: The Curse of Clyde Langer) The fictional superhero Spider-Man was able to scale buildings by crawling along their sides, not unlike a spider. (PROSE: To the Slaughter)
Amy Pond named her and Rory's daughter Melody Pond; to her, this was the name for a superhero. (TV: A Good Man Goes to War)
Behind the scenes
As he revealed at the 2016 New York Comic Con, at the age of six, Steven Moffat was the superhero "Red Rat", "for most of an afternoon". He made a costume, and patrolled Paisley for an hour in search of crime.