What do Italian Renaissance painters, pizza and ninjutsu (ninja martial arts) have in common? These four rad brothers: the Teenage Mutant Ninja Turtles! These gnarly dudes were at the forefront of gaming in the '90s and could be seen everywhere—on televisions, movie screens, and merchandise like lunch boxes and backpacks. Trained in ninjutsu by a giant anthropomorphic rat, these "turtle boys" have been battling crime in side-scrolling and fighting games since 1989.

Ninja characters are often found in action-adventure games, where their speed and agility lead to some awesome moves. However, Shadow breaks the mold as one of the few playable ninja in a role-playing game. Shadow makes his debut in Final Fantasy VI, preferring to throw weapons like shuriken (ninja stars) from the back row while his faithful dog Interceptor occasionally protects him from damage.

What's cool about Shadow is that he's a freelance mercenary intermittently working for the protagonists. He leaves the party at will and only joins up permanently if you've fulfilled certain critical game conditions. Also, the only way to get to know his backstory is though a series of dreams, meaning he actually lives by the ninja code of secrecy.

Psylocke may not have as many video games appearances as some of the other characters, but her power and versatility cannot be denied. The sister of Captain Britian, Elizabeth Braddock had her mind, and telepathic powers, swapped into the body of a Japanese assassin.

Armed with her mutant powers as well as her newfound ninja abilities, Psylocke became one of the deadliest X-Men. As a playable character, she's known for her swift combos mixed with her telekenetic blade that can cut through her enemy's psyche. Fans are especially excited to see her in a larger role in the 2016 Marvel film X-Men: Apocalypse.

One of the fiercest rivalries in video game history—and arguably the most violent—the deeply-entwined story of Scorpion and Sub-Zero from Mortal Kombat makes it difficult to choose only one. Born from two rival ninja clans, theirs is a complicated story of death, revenge, resurrection... rinse and repeat. But while the two seem to have hugged it out in recent games, who knows how long the truce between these two "frenemies" will last.

A teenage master of ninjutsu—and controversy—Ayane had a very difficult childhood as the "cursed" half-sister of clan princess Kasumi. In her first appearance as a playable fighter (Dead or Alive 2), she's the antagonistic assassin looking to kill Kasumi. But after winning the third Dead of Alive Tournament, her popularity (and bust size) grew substantially. To date, she's appeared in all DOA sequels and spin-offs, and has been featured in other game series such as Ninja Gaiden and Dynasty Warriors, earning her a respectable spot on our list.

Interesting to note: a major criticism of her character is her age and sexuality. Her age was not released in several Western ports for fear of child pornography lawsuits and censorship laws. But as of Dead or Alive 5, her age has been canonically changed from 14 to a more legal 18 years old.