Worf

Worf was the Klingon chief of security of the USS Enterprise in the 24th century. While on the Enterprise, the Eleventh Doctor recognised him as a Klingon, but noted that his memories were being altered. Before he saw Worf, the Doctor had never heard of them. (COMIC: Assimilation²)

He attended the Dæmon Bonjaxx's birthday in his bar on the space station Maruthea, as did the Seventh Doctor and Ace and a future incarnation of the Doctor and his companion Ria. (COMIC: Party Animals)