Frankie Mash Jr.: Four-year-old student at Pitchfork Pines Preschool who is a Frankenstein monster with super strength and a super stomp (voiced by Erin Mathews).

Personallty: A well respected young monster. He is part of the Super Monsters. Frankie is 4 years old. His power is super strength and electricity manipulation. He is kind, and sometimes clumsy and impulsive. And he loves playing a stacking game when both in human form and super monster form. He is from the same family as Hank and the maternal cousin of Hank N. Stein and his mother, Mary's maiden name is Stein and Mary is the younger sister of Frankenstein/Frank Stein and he is also the nephew of Frankenstein/Frank Stein. He is a half-human-half Frankenstein hybrid.

Appearances:

1. As a human, Frankie has brown hair and beige skin. He has brown eyes with light blue eyeglasses and wears purple and green striped shirt. He wears blue pants, a wristwatch on his left wrist and green shoes.
2. In Super Monster form, he has black hair with a long unibrow, green skin with a bandage on his forehead and same brown eyes. Frankie wears the same purple and green striped shirt and blue pants, but no wristwatch and shoes.
3. After making a monster match with Jerry the jackalope, Frankie's pocket shirt changes from purple to green with lightning bolt, and has monster size (mega size or Frankie size).

Trivia: Everytime Frankie says he makes a mistake all the time, he tends to punctuate the sentence by finishing the sentence reiterating the "All The time" part. (Ie: I break things all the time. All the time).