Anna will assume the role of Cassie, one of the most attractive, available, and — as Ted discovers — unfortunate guests at the big event. Ellie Kemper had to bow out due to a scheduling conflict.
Anna will appear in one episode, but, given the wedding’s season-long structure, it’s possible she could return.
Congratulations Anna, but be sure not to get too comfortable, we hope to see Sarah Newlin on True Blood, too!
source: TVLine.com