Kickstart

Kickstart (also written as KickStart), is a sidekick Batman got after Robin was killed by Doctor Octopuss in the Lego Batman, Spider-Man, and Chewbacca Movie, in which he has only been mentioned in the end of the movie and hasn't been seen or shown in any other episodes at all.

Trivia

 * KickStart sounds like the name of a real superhero.