I looked it up on ESPN---Bill Stoneman had 2 (One in the Expos inaugural year), Charlie Lau had one, and the last one was Dennis Martinez' perfect game.
If people outside Montreal don't remember Charlie Lau's no-hitter it might partly be because Len Barker of the Indians threw a no-hitter against the Blue Jays five days later.
Dick Bosman, who was the expansion Senators' best pitcher while they were in DC threw a no-hitter for the Indians in 1974.
