|In Mortal Kombat|
—Unit 5's Battle Cry
Unit 5 can see through Reptile's cloaking ability, something that makes the saurian understand that he will need better camouflage to ambush Cyrax and Sektor. He can only be damaged by acid in the challenge, so he is invulnerable to physical attacks.
Not much is known about Unit 5's history. He appeared as a cyborg working for the Lin Kuei, whose goal was to target Reptile. After targeting Reptile, he reported to Cyrax and Sektor using his communicator but before they could arrive at his location, Reptile killed him and took possession of his armor.
Under the disguise of Unit 5, Reptile attacked Sektor with the Acid Spit attack, giving away his cover.
- While Unit 5's first appearance is of a gray version of Cyrax, when Reptile steals his identity, he looks similar to Cyber Sub-Zero, but with green plates.
- In the Mortal Kombat: Legacy episode, "Cyrax and Sektor", a Lin Kuei cyborg known as Hydro battles the two cyborg ninjas. Hydro bears a resemblance to Unit 5.