I can think of 2: Robert Llewellyn played Kryten in US Red Dwarf and Elizabeth Bennett played housekeeper in American version of Home To Roost.

The IT Crowd, the same actor plays Moss in the original and a U.S. pilot that was shot.

I know there must be more, since we can't help taking one of your brilliant programs and putting out some half-assed bastardized version of it. And then we think we're all clever by keeping the same dialogue, which makes no sense to us. Arghhh!!!! Coupling being the obvious example of this.