|First Appearance||"Sanctuary (Part 1)"|
|Last Appearance||"Sanctuary (Part 2)"|
|Allegiance||7th Massachusetts Militia Regiment|
|Age||Early to mid 40's|
|Occupation||7th Mass Commander (Post-Invasion)|
|Cause of Death||Shot in the chest by Tom Mason.|
|Terry after being shot by Tom.|
|“||Mike they didn't want to die anymore than we do, but they have their missions to, I mean it sounds crazy but it's like every group has to hit it's numbers, once we understood that once we knew what they wanted and what they didn't want.. an arrangement just evolved.||”|
— Terry to Mike about the skitters.
Lt. Terry Clayton was the Commander of the 7th Mass. He was old friends with Mike and Daniel Weaver. Terry was working with the Espheni to trade in kids, lying to the 2nd Mass to bring their kids to the Sanctuary to be traded in.
The 7th Mass was completely wiped out, and he is one of 20 known survivors. He was working with the Skitters trading kids for safety. Pope came across their base attempting to steal some food from them, Clayton interrogated Pope, who unwillingly gave up information regarding the 2nd Mass. Clayton went to the 2nd Mass and lied to them convincing them to send their children with him, and lies to the 2nd Mass about the upcoming alien attack and the 3rd Mass joining forces with the 2nd Mass. Later that night when they arrive to the base he convinces one of the children, Eli, to go with him, saying he can see his parents, however Clayton gives him over to a Skitter, revealing he is working for them now. Terry also tells them that he will be bringing more soon.
Terry escorts Fuller and O'Brian back to the main road so that they can arrive back to the school, however takes a detour and shoots them both, then collects apples and brings them back to the sanctuary saying that he took a "detour". Greene approaches Terry and they both go to the barn where John Pope is being held and tries reason with him to make him join the 7th. At dinner Terry asks Rick Thompson if he's hungry but Rick does not reply, then asks Ben how he can eat "their" food. After Mike finds the secret about the 7th, terry finds him in the barn and reasons with him that he only does it for protection for his men and their family. The 7th Mass's secret was discovered and the 2nd Mass kids escaped from the 7th Mass base he and his men gave chase but were temporarily stalled by Mike despite him saying earlier he liked Mike, he killed him. He and his men tracked the children down they briefly fought Pope brought the children and Tom back to the 7th Mass base where the 2nd Mass came out of their base and a couple men were shot. He was shot to death by Tom Mason after he attempted to pull a pistol on Hal.
|Season 1 appearances|
|Live and Learn||The Armory||Prisoner of War||Grace||Silent Kill|
|Sanctuary (Part 1)||Sanctuary (Part 2)||What Hides Beneath||Mutiny||Eight Hours|