Brill

Brill was a Werelok who led the Werelok attacks on the various human colonies in the New Earth system. While the Doctor and K9 were helping Joe Beam and Babe defend their cargo freighter from a werelok attack, Brill scratched the Doctor, which would turn him into a werelok. The Fourth Doctor entered the TARDIS and exited out of time and space to find a cure, and then returned. (DWM: The Dogs of Doom)