When Arnold receives Mr. Hyunh's name in the boarding house's annual Secret Santa draw, he decides to make it the most special Christmas ever for the lonely boarder, and tries to reunite Mr. Hyunh with his long-lost daughter. Meanwhile, Helga agonizes over what would make the perfect present for Arnold.
| Actor | Role |
|---|---|
| LLane ToranArnold (voice) | Arnold (voice) |
 Francesca Marie SmithHelga Pataki (voice) | Helga Pataki (voice) |
 Jamil Walker SmithGerald Johanssen (voice) | Gerald Johanssen (voice) |
 Tress MacNeilleGrandma Gertrude (voice) | Grandma Gertrude (voice) |
 Dan CastellanetaGrandpa Phil (voice) | Grandpa Phil (voice) |
 Maurice LaMarcheBig Bob Pataki (voice) | Big Bob Pataki (voice) |
 Kath SoucieMiriam Pataki (voice) | Miriam Pataki (voice) |
 Olivia HackRhonda Wellington Lloyd (voice) | Rhonda Wellington Lloyd (voice) |
| CChristopher WalbergStinky Peterson (voice) | Stinky Peterson (voice) |
 Anndi McAfeePhoebe Heyerdahl (voice) | Phoebe Heyerdahl (voice) |
 Baoan ColemanMr. Hyunh (voice) | Mr. Hyunh (voice) |
 Hiep Thi LeMai (voice) | Mai (voice) |
 Vincent SchiavelliMr. Bailey (voice) | Mr. Bailey (voice) |
 Dom IrreraErnie Potts (voice) | Ernie Potts (voice) |
| SSteve VikstenOskar Kokoshka (voice) | Oskar Kokoshka (voice) |