Greg Ellis is an American actor that has appeared in movies, TV series and video games. For Phineas and Ferb, he provides the voice of Jameson in "The Monster of Phineas-n-Ferbenstein" and additional voices in other episodes.
- Bob Stonefire, Heavy Gear (TV series)
- Michael Amador, 24
- Lieutenant Theodore Groves, Pirates of the Caribbean film series and video games
- Star Trek: Cardassian Ekoor in Deep Space Nine, Chief Engineer Olsen in the 2009 film
- Simon Cochran, Trust Me
- Ari Valentine/Ares, Valentine