Trevor Spacey is one of the main characters found in Metal Slug 4.
"I'm going to make scrap metal out of you, pal!!" - Trevor's pet phrase
Trevor received his first computer at the age of three as a gift from his parents, and completely understood binary codes and computer languages by the age of seven. During his summer recess from school, he usually worked on creating anti-virus programs for his home-work assignments, still used by his school against growing threats from the Internet. His ability to understand computer languages enabled him to be assigned to the scout regiment of the Regular Army. Finding respect for Marco, he then signed up enroll into the Peregrine Falcons - later on Trevor became to be a Sergeant in the P.F. Squad. There are rumours that after the events against the Amadeus Syndicate he retired to the Regular Army work as a security programmer.
While Trevor plays the same as any other character, his standing melee attack involves kicking his foes with his knifed boots. Unfortunately, it hinders his movement as he either slows down or stops when he attacks.
Originally a cameo in the game's POW list, he (alongside Nadia) later becomes a purchasable unit. He uses his Knife Boots as his close-range attack and Two Machine Guns as his long-range and special. When Trevor activates his special, he jumps backwards while shooting. Initially he was a powerful unit, though he was nerfed by a subsequent update.
Trevor returns in Metal Slug Attack, now re-established as part of the main cast (seen as early as the game's opening cutscene). Unit parts of him can be earned by the Daily Login, the POW Shop, or as a random reward in POW Rescue. His new ability is to dodge enemy attacks by jumping back while simultaneously shooting at them.
A new version called Special Trevor is introduced in the "Amadeus Revenge" event as $20 Pre-Acquisition unit. Donning a darker set of clothes, Trevor swaps his Two Machine Guns for the Enemy Chaser. He can no longer retreat nor dodge attacks. He and Rumi make the "Support Troops" team.
Zombie Trevor has a new sound effect that mimics those from Metal Slug 3 (he originally had an echoed scream rather than a gurgled one).
Abigail, a Rebel officer introduced in this game, has a crush on Trevor, which he is not aware of. In fact, if he, his special form, or the Motorbike POW Ver. 2 appear in either the player or opponents deck, then Abigail will blush. Beatriz, Abigail's sister, is annoyed by this, although it's unknown if she has any sort of history with Trevor.
- Trevor and Marco swap their screams when they die in their zombie forms in Metal Slug 4.
- Excluding NPCs, Trevor is the only character in the game to have white hair.
- Trevor is the first male character in the series to have his own unique melee attack; the Knife Boots.
- After the events of Metal Slug 4, Trevor and Nadia's whereabouts are unknown, as they have yet to make another appearance in the main series.