|Affiliations|| Forever Knights|
Negative Ten (formerly)
|Powers and Abilities|
|Abilities|| Martial Arts|
|Equipment|| Specialized Armor|
|Alias|| Forever Knight Ninja|
Ninja Boy (Four Arms)
|Voice Actor||Kevin Michael Richardson|
|First Appearance||Perfect Day|
It first appeared in the end of Perfect Day, and made another appearance in Ben 10 vs. the Negative 10: Part 1 and Ben 10 vs. the Negative 10: Part 2, where it was defeated by Perk Upchuck, who spat it's own shurikens back at it.
The Forever Ninja is also seen in An American Benwolf in London, but later defeats itself by holding the Proto-Tool backwards and shooting an energy blast at itself, but was salvaged by a mutated Chadwick.
Powers and Abilities
The Forever Ninja has enhanced strength, speed, agility, stealth and battle tactics.
The Forever Ninja has a limited self-repair system to repair minor damage.
The Forever Ninja has an assortment of weapons, including energy swords and various shurikens and throwing projectiles.
Loud noises such as sonic booms or the large bell of the Big Ben Clock Tower can disrupt the Forever Ninja's system.
If the Forever Ninja takes enough damage, it will shut down.
Its Artificial Intelligence is not as advanced as some of the other robots seen in the series; While holding the Proto-Tool, the Forever Ninja accidentally shot itself in the chest due to holding it backwards.
- Perfect Day (first appearance)
- Ben 10 vs. the Negative 10: Part 1
- Ben 10 vs. the Negative 10: Part 2
Ben 10: Omniverse
- Some Forever Ninjas appear in Ben 10: Alien Force (Video Game) and Ben 10 Ultimate Alien: Cosmic Destruction (in Tokyo)
- Despite being called the "Red Knight", it's color is more of a brownish-maroon, until Ben 10: Omniverse, where it is crimson red.
- The raised portions on the back of the Forever Ninja's head resemble the ears on the cowls of DC's Batman and Marvel's Black Panther. Both of these characters fight with similar ability to the Red Knight. It is slightly similar to Marvel's Deadpool.
- The Forever Ninja has a resemblance to Snake Eyes from G.I. Joe.
- The Forever Ninja spoke in Ben 10: Alien Force: The Video Game, but never has in the actual show.