Overkill's body is amorphous consisting of a dark goo-like substance. He can shape himself in various ways but usually features two elongated eyes and a large mouth with numerous sharp teeth.
The Omnitrix symbol is located on his forehead.
- Shapeshifting- Overkill can change his shape, even forming weapons such as axes and maces.
- Sharp Appendages- Overkill can form his appendages into sharp objects such as knifes, talons and blades.
- Elasticity- Overkill can stretch his bodies and form tendrils.
- Enhanced Durability- Overkill's body is extremely dense allowing him to survive most attacks.
- Enhanced Strength- Overkill possesses superior strength.
- Power Enhancement- Overkill can cover a host's body and greatly enhance their abilities.
- Sharp Teeth- Overkill's teeth are sharp enough to bite through flesh.
- Memory Sharing- Overkill is capable of sharing his memories to the host.
- Sound- Overkill is sensitive to loud and high pitched noises, however enough exposure over time can help him develop a stronger resistance to this.
- Heat- Overkill is vulnerable to fire and intense heat.
- Overkill is largely based on the Marvel Comics character, Venom.
- Planet Tonrom's name is a combination of the first names of Tom DeFalco and Ron Frenz, the original creators of Venom.
- Similar to Shock Rock from the Reboot, Overkill has the ability to power up some of Ben's other transformations.
- Overkill is part of the Omnitrix's Parasite Playlist and is able to cover and enhance the abilities of other transformations. However, he is unable to cover any fire, sound or energy-based aliens. He also has a limit to how big of an alien he can enhance, such as Humungousaur, who, in his full size, would be far too large to cover.