How I Met Your Mother Exclusive: The Office's Ellie Kemper Joins Final Season

How I Met Your Mother Casts Ellie KemperThe guest list for Barney and Robin’s How I Met Your Mother nuptials continues to grow.

TVLine has learned exclusively that The Office‘s Ellie Kemper is joining the CBS hit’s ninth and final season.

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Kemper will play Cassie, “one of the most attractive, available, and — as Ted discovers — unfortunate guests at Barney and Robin’s wedding,” according to series co creators Carter Bays and Craig Thomas.

As of now, Kemper is set to appear in one episode.

Other previously announced castings for the season-long weekend wedding storyline include Wayne Brady returning as Barney’s brother and Cristin Milioti (now a series regular!) as The Mother. The View‘s Sherri Shepherd is also set to recur as a nemesis to Marshall.

HIMYM‘s farewell season kicks off Sept. 23.