Ben and a mysterious girl from his past must prevent an alien threat from destroying the world.
Ryan Kelley
as Ben Tennyson
Galadriel Stineman
as Gwen Tennyson
Nathan Keyes
as Kevin E. Levin
Alyssa Diaz
as Elena Validus
Herbert Siguenza
as Victor Validus
Barry Corbin
as Grandpa Max Tennyson
Dee Bradley Baker
as Big Chill / Humongousaur (voice)
Alex Winter
as Nanomech (voice)
Wendy Cutler
as Alien Chip Queen (voice)
Joyce Kurtz
as Computer (voice)
Patrick Cox
as Big Ed
Jeremy DeCarlos
as Helio
