DC has a number of 'last members of a dead race' type characters.
I would like to try and list them.
Superman, Supergirl, Powergirl, Superboy Prime, 3d Kryptionian on earth, Kryptonian boy (Identity unknown)
Zod. (Will be)
Kandor City (Number unknown)
Argo City (Number Unknown)
Phantom zone villains (Number unknown)
Match (Quarter clone) (A clone of half a clone )
Krypto (Pseudo Krypton)
Alternate reality versions from the Superman/Batman series, including a future superman.
J’onn J’onzz, Miss Martian (White), 5 other Green Martians, (All males, 1 child).
Element Lad (Legion)
Mano (Fatal Five - Legion).
Triplicate Girl (Legion)
Princess Projectra (Legion)
Kilowog (Green Lantern)
Mogo (Green Lantern)
Please feel free to add more.