Stephen Colbert to Guest Star on 'The Office'.

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The host of The Colbert Report is reporting for comedic duty on The Office! Stephen Colbert will guest-star this season as Broccoli Rob, a former member of Here Comes Treble, Andy’s a cappella group, EW has learned. In the Halloween-themed episode, Andy (Ed Helms) discovers that the smarmy, competitive Broccoli Rob is singing a different tune about the history of the group and stirring up drama, which only intensifies the rivalry between these two frenemies.

Colbert — who worked with Helms and former Office star Steve Carell at The Daily Show — will pop up on the October 25 episode. The ninth and final season of The Office begins tonight on NBC at 9 p.m.

Source: EW.com.