Cathy Overton-Clapham (born Cathy Overton, July 19, 1969) nicknamed "Cathy O" is a Canadian curler.
Overton-Clapham is one of Manitoba's most decorated female curlers, with one world championship, five national championships, and twelve Scotties Tournament of Hearts appearances.
In 2019, she began coaching the Jamie Sinclair rink.In 2019, Overton-Clapham was named the fifth greatest Canadian curler in history in a TSN poll of broadcasters, reporters and top curlers.