Yassen Gregorovich was a Vortixx, and was one of the best assassins in the Matoran Universe. He was hired by Blackout in order to bring Ynot to Destral, a mission that he survived. He was also the former owner of one of three armour-piercing heat guns in existence. Ravat assaulted him and stole it, while also removing one of his arms and an eye. From that point onwards, he decided to use a wheelchair, despite both of his legs being fine.
His status is unknown after the destruction of the Matoran Universe, though it was implied that he is now living on the Red Star.
- Yassen Gregorovich is based on a villain of the same name in the Alex Rider book series.