The first XBOX game platform was released in 2001 and got around 600 games till 2008. There are not many XBOX exclusive games and game characters. Big noteable games are the Halo and Gotham Racer series with characters like Master Chief and Cortana  

 

Video Game Characters first seen on the first XBOX

Blinx

Blinx

Christie (DOA)

Christie

Cortana

Cortana

Master-Chief

Master Chief