Thug was originally a member of Technet and later the Special Executive. (COMIC: Sid's Story)
Behind the scenes[]
Thug is identified as a "loom-born Gallifreyan" in Marvel's X-Men: Phoenix Force Handbook.

Members of Thug's species in Top 10.
Members of Thug and Legion's species cameoed in Alan Moore's comic story You Better Watch Out You Better Not Cry... for Top 10.