<P> Benjamin "Ben" Koldyke (born March 27, 1968) is an American actor who was most recently seen starring in Mr. Robinson for NBC . </P> <P> Originally a high school English teacher and football coach in Chicago, Koldyke's acting career received a jump start after a chance encounter with It's Always Sunny in Philadelphia creator - star, Rob McElhenney . Regulars at the same Venice cafe, he covered Rob's tab with a note that said he "thought his show was fantastic," and this exchange led to Koldyke's first (of many) TV pilots, Boldly Going Nowhere for Fox, a few years later . </P> <P> After Boldly was not picked up, Koldyke went on to book recurring roles as Dale Tomasson in the HBO series Big Love and as Don Frank in How I Met Your Mother for CBS . </P> <P> In 2012, Koldyke starred as the lead character in the short - lived ABC comedy series Work It and later guest starred in HBO's The Newsroom. 2013 saw him star in another ABC sitcom, Back in the Game, opposite James Caan and Maggie Lawson . He has recently been seen in a significant arc on Showtime's Masters of Sex as teacher and football coach Paul Edley . </P>

Who played don on how i met your mother
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