Here are three examples:
Mayor Richard Wilkins (Buffyverse), because he goes by Richard Wilkins III.
Crime Syndicate (DC), because they hail from Earth-3.
Three-Headed Giant (Monty Python and the Holy Grail), for obvious reasons.
Mr. 3 from One Piece
Rick D. Sanchez III
Metal Sonic 3.0
Todd Ingram
Lawrence III
Alison Hargreeves
Stepford Cuckoos (Comics & The Gifted)
Henry J. Waternoose III
King Ghidorah
And of course...
Third Sister from Obi-Wan Kenobi
The trio (Max Payne)
Negative Numbuh 3
What do you think?