VIDEO : NBC Adds To Its Lineup For A Legendary Christmas Special

John Legend and Chrissy Teigen are rounding out the guest list for their upcoming NBC holiday special, ?A Legendary Christmas with John and Chrissy,? with Stevie Wonder, Kenan Thompson and Zach Galifianakis all set to appear on the hour-long telecast, TheWrap has learned exclusively. While the longtime ?SNL? cast member is making a ?special cameo? and Galifianakis is turning up as a party guest (with ?comedic moments?), Wonder is going to lend Legend a hand in the music department.