Trevor Belmont is the main protagonist of Castlevania III and also returns in Castlevania Curse of Darkness, as a hidden unlockable character. His latest appearance was in Castlevania Judgement. 

Back in 1989 when Castlevania III was released, Trevor looked a lot like Simon, on both the game as well as in the official artworks but his design was changed a lot for Castlevania Curse of Darkness. Now he looks much more unique and like quite the badass character he is!

In Japan, Trevor is known as Ralph btw.

Trevor never reached the popularity of Simon or Alucard though, it will probably take a good while until this fan art gallery has more than just one entry.

 Trevor-Belmont

Trevor Belmont from the Castlevania Series Fan Artby the Game Art HQ Community:

Castlevania Tribute - Trevor_Belmont

Trevor Portrait