- Kyle Labine as Evan Ross
- Sarah Podemski as Andy
- Corinne Conley as Aunt Kathryn
- Joy Tanner as Sarabeth
- Mark Benesh as Curtis
- Mark Melymick as Dad
- Janet Land as Mom
- Ashley Dawn Brown as Julia (uncredited)
While staying with his weird Great Aunt Kathrine, Evan and his new friend Andy find a jar labeled "Monster Blood" in a room Aunt Katherine instructed Evan must not enter. It's fun to play with at first. And Evan's dog, Trigger, likes it so much, he eats some! But then Evan notices something weird about the green, slimy stuff--it seems to be growing. And growing. And growing. And all that growing has given the Monster Blood a monstrous appetite.
Differences from the book
- Evan and Andy find the Monster Blood in a room Kathryn forbid them from entering. In the book, they bought a can of Monster Blood at an old toy store.
- Trigger is a collie mix instead of a cocker spaniel.
- The twin bullies were omitted.
- Kathryn is not deaf.
- In the TV version, the cat turns out to be a young witch who used to stay with Kathryn, but was almost thrown out for practicing witchcraft (which is what the Monster Blood is) until she used magic to turn herself into a cat.
The Monster Blood DVD was released in 2008 to celebrate the release of Goosebumps HorrorLand, and was released alongside the A Night in Terror Tower and One Day at HorrorLand DVDs. The DVD features the following episodes: