Gregor Campbell was a childhood acquaintance of Montgomery Scott from Scotland. After Scott's graduation from Starfleet Academy in 2242, he returned home to proudly show off his officer's uniform; Gregor and Sean Toricelli ridiculed and mocked Scott and his decision to enlist. (Star Trek novel: Engines of Destiny)

It is possible, but never established, that Gregor was related to Glynnis Campbell.