John de Lancie played Allen Shapiro in the Torchwood stories End of the Road, The Gathering and The Blood Line.
He is probably best known for his recurring role as Q in Star Trek: The Next Generation, Star Trek: Deep Space Nine and Star Trek: Voyager from 1987 to 2001. He is also known for voicing the Q-like Discord in My Little Pony: Friendship is Magic from 2011 onwards.