The Heavy Unit is one of the toughest Units in Mech Mice Tactics. It uses Heavy Blasters and Heavy Suits for high damage combat. However, they are quite slow and require many turns to move from place to place. The two known Heavy Units are Flank and Pi.
- Combat: A high damaging combat unit with large health that can soak up enemy hits easily without the need to use many Healing Flowers.
- Base health: High; he is best used as a up-front unit to soak up damage rather than weaker units.
- Movement Range: 1 (+3 for sustained).
- Primary attack: High damaging Heavy Blaster.
- Special ability: Doom Spin- the Heavy does a spinning combo attack that takes down all surrounding small bugs in a single hit.
- Cons: The Heavy is a proficient combat unit that can handle enemy encounters single-handedly, but is deficient in moving to further places quickly, using up many turns to reach a specific area and has to sometimes move closer to enemy bugs to be within firing range.
- They use many high damage items.
- It is possible that the Heavy's design was inspired by Team Fortress II (a computer game).
- It is the third playable class of Mech Mice Academy.
- It has a 12 shot per second megablaster in Mech Mice Academy.