Alyson Hannigan joins 'The McCarthys' in Christmas guest role
The 40-year-old actress will play Pam, Marjorie and Arthur's upstairs tenant in the CBS show's Christmas episode, reported Entertainment Weekly.
The character of Pam is described as "sweet", but also broken-hearted following a recent break-up.
In a bid to cheer Pam up, Marjorie invites her to join the family for Christmas Eve. Pam, however, is shocked at the way the family treats each other during a competitive exchange of gifts.
The episode will air on CBS on December 18.
Hannigan played Lily in 'How I Met Your Mother' and Willow Rosenberg in 'Buffy The Vampire Slayer'.