|This article belongs to the Classic Timeline|
The Nuclear Fusion Grenade first appeared in the episode War of the Worlds: Part 2.
In Ben 10: Alien Force, the Nuclear Fusion Grenade looks like a short pipe.
In Ben 10: Ultimate Alien, the Nuclear Fusion Grenade looks like a colored light-blue sphere, with blue stripes at the top, bottom and the middle. Three back holes are located in the right and left side and a giant black hole covers the middle.
In The Enemy of My Enemy, Octagon Vreedle used it against Ultimate Kevin, but because of his lack of intelligence, he forgot to consider the fact that it had the power to destroy the entire Plumbers' Academy space station along with everyone in it. Ultimate Echo Echo took the bomb out into space away from the academy and let it explode there, not harming anyone.
- War of the Worlds: Part 2 (first appearance)
- The Enemy of My Enemy (first reappearance)