US TV
In the episode - airing January 25 in the States - Farrell will play a "life-loving" Irishman called Billy Callahan. The role marks his debut on primetime TV in America.
"Colin is not only the quintessential good guy/big star, but he should definitely be doing more comedy," said an executive producer Bill Lawrence. "He's fantastic."
Farrell is also taking up hosting duties on this week's Saturday Night Live.
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