Greg Ellis (born 21 March 1968) is an English actor. He has worked on films such as Star Trek as Chief Engineer Olsen the original engineer of the Enterprise, Pirates of the Caribbean: The Curse of the Black Pearl, Titanic, Pirates of the Caribbean: At World's End and Pirates of the Caribbean: On Stranger Tides, "Beowulf", To End All Wars, and Mr. and Mrs. Smith and has appeared in television shows such as "Trust Me", "X-Files", "Valentine", "Nip-Tuck", "Knight Rider", Star Trek: Deep Space Nine (in its final episode, "What You Leave Behind") and in the third season of 24 as the biological weapons dealer, Michael Amador.

He also has a steady voice over career, giving voices to the games SOCOM II: U.S. Navy SEALs, Star Wars: Knights of the Old Republic II: The Sith Lords, Tomb Raider: Legend, SOCOM 3: U.S. Navy SEALs, Ty the Tasmanian Tiger, and to cartoons such as The Grim Adventures of Billy & Mandy, Invader Zim and all three series of the Ben 10 franchise. His voice was also featured in the PlayStation 2 games Rogue Galaxy, as the character Simon Wicard, Cait Sith in Dirge of Cerberus: Final Fantasy VII, and Tomb Raider: Underworld as Alister Fletcher.

Recently, Ellis has played Commander Giles Price in the game Command & Conquer: Red Alert 3. He has voiced Cait Sith in the English version of the CGI film Final Fantasy VII Advent Children, and played the voice of Garmund in the Robert Zemeckis animated film Beowulf.