In New York City for their annual tradition of Christmas Eve debauchery, three lifelong best friends set out to find the Holy Grail of Christmas parties since their yearly reunion might be coming to an end.
| Actor | Role |
|---|---|
 Joseph Gordon-LevittEthan | Ethan |
 Seth RogenIsaac | Isaac |
 Anthony MackieChris | Chris |
 Lizzy CaplanDiana | Diana |
 Jillian BellBetsy | Betsy |
 Mindy KalingSarah | Sarah |
 Michael ShannonMr. Green | Mr. Green |
 Lorraine ToussaintMrs. Roberts | Mrs. Roberts |
 Randall ParkBoss | Boss |
 Ilana GlazerRebecca Grinch | Rebecca Grinch |
 Nathan FielderJoshua | Joshua |
 Heléne YorkeCindy | Cindy |
 Aaron HillTommy Owens | Tommy Owens |
 Tracy MorganNarrator / Santa | Narrator / Santa |
| DDarrie LawrenceNana | Nana |
 James FrancoSelf | Self |
 Miley CyrusSelf | Self |
 Kamal Angelo BoldenKamal | Kamal |
 Baron DavisSelf | Self |
| CChuck MucklePiano Playing Uncle | Piano Playing Uncle |
| CCurt BourilCindy's Husband | Cindy's Husband |
 Brooke LiddellCindy's Daugher | Cindy's Daugher |
 Kiley LiddellCindy's Daughter | Cindy's Daughter |
 Jason MantzoukasBad Santa #1 | Bad Santa #1 |
 Jason JonesBad Santa #2 | Bad Santa #2 |
 Clem CheungDeli Owner | Deli Owner |
| HHarolyn BlackwellOpera Singer | Opera Singer |
 Natalie KneppCoat Check Girl | Coat Check Girl |
| CCameron Earl ThriftSinging Kid | Singing Kid |
| JJeremy VimesHunan Waiter | Hunan Waiter |