Fanboy (noun)

1. An enthusiastic and devoted fan, especially of a particular comic book, movie, or video game.
2. An enthusiastic and devoted fan, especially of a particular comic book, movie, or video game, and known for their excessive enthusiasm and loyalty.

Origin:

Slang term, origin is unclear, but likely a blend of the word "fan" and "boy".

Examples:

1. The fanboy had all the merchandise for his favorite comic book series.
2. The fanboy dressed up as his favorite video game character for the convention.
3. The fanboy was known for his excessive enthusiasm for the movie franchise.
4. The fanboy was a regular at the comic book store, always looking for the newest issues.
5. The fanboy was always the first in line to see the latest film in the series.