Daphne's least favorite brother, Simon (played by Australian Anthony LaPaglia) has a terribly unconvincing accent. Mostly played for laughs, though.
See also any guest actor (not-British) playing Daphne's random boyfriends in earlier series. See British Accents above.
Jane Leeves is British but cannot do a Manchester accent for toffee. God help the woman if she ever needed directions to the Trafford Centre. Word Of God is that they wanted Daphne's accent to be working class and understandable to Americans so Jane Leeves adopted that particular accent. [1]
Gil Chesterton is played by an American-born English actor and displays many symptoms of I Am Very British. In one of the first episodes, Frasier comments on his "phony accent."
Hey, It's That Voice!: It was not uncommon for celebrities to make cameos as callers to Frasier's show.
The final episode of many (but not all) seasons replace the usual end of episode gag with a "thanks for calling" montage listing the cameos made that season.
