Will Ferrell to appear in 'The Office'
NBCs popular show, The Office, will have funny man, Will Ferrell, guest star in some of this season's episodes.
Ferrell will play a visiting branch manager over several episodes.
Carell's farewell is expected four episodes before the season finale of "The Office."
In preparation of his exit, NBC is bringing in high-profile guests, including "The Office" creator Ricky Gervais, reprising his role as David Brent.
Gervais will make a cameo in Thursday's episode.