The X series are a series of Transgenics, specifically those that look entirely human.
All have barcodes on the back of their necks and most answer to their designation.
The X series was created by Manticore to be super soldiers.
- Dalton - X6-???
- Bullet - X6-787 - Was given his name by Max Guevara because he was shot when his group were ambushed during an attempt to return to those aligned with Manticore .
- Fixit - X6-809 - Was given her name by Max Guevara in Season 2 because she could 'fix' everything. She showed this skill when she fixed a broken down truck.
- Zero - X6-???
- Ralph - X6-??? - Was named by Max Guevara because she vomited after watching a bullet being removed from Bullet's body.