Shredder

"I am Oroku Saki, Ninja Master of the Foot Clan. The Foot have existed for centuries, and they will live on for centuries more, with me at their helm. I am unstoppable. I reign supreme in the Clan, as I will one day the entire Earth... and beyond. Rejoice that I honor you with these words, o worm! Bow before my magnificence and might, and I may spare you when my time arrives. But only if it pleases me to do so! Who I am and what I do is none of your concern! Merely prepare yourself for the inevitability of my reign! I have spoken! Be gone with you!"

- The Shredder

The Shredder is the main villain in most Teenage Mutant Ninja Turtles media, and has a lot in common with Darth Vader. In most media he is depicted as the leader of The Foot Clan and his relation to Splinter the rat as enemies, and that Splinter raced the turtles that like him are Mutants, thanks to ooze. The turtles fight The Shredder quite a bit.

Story
Each of the TNMT media give a different origin for both the Shredder and the turtles. But all have something in common that Oroko Saki raised through the ranks of the Foot Clan, becoming their leader. He also had a rivalry with a man named Hamato Yoshi, for various different reasons in each depicting, but in all Saki wanted revenge on Yoshi. Yoshi traveled for the United States because he didn't wanted to face Saki, but saki followed him and killed him. In all versions, Yoshi had a pet rat named Splinter, who learned ninjutsu by mimicking his moves. when Yoshi was slain, Splinter jumped on Saki and scarred him on the face just to be thrown away by Saki. Splinter hid in the sewers, where both him and four small turtles that felt from a truck were contamined by a chemical substance called ooze. All of them mutated into giant, rational selfs. Splinter, knowing that Saki would pose a great danger to the world, decided to teach ninjutsu to the turtles, so they could fight the Shredder, as he became known.

In the 1987 cartoon, the Shredder forms a alliance with Krang, a mutant and ruler of Dimension X who felt on Earth by accident. By using Krang's intelligence and technology, he replaced the foot clan for ninja-cyborgs. Here, Yoshi and Splinter are the same person.

In the 2000 cartoon, the Shredder is actually a alien utrom known as Ch'rell. He was imprisoned and was being transportated in a ship by other utroms. He saboted the ship, making it fell on Earth. Without a way to go back home, the utroms decided to disguise themselves amongst the humans, until their technology advances to a point that allow them to return home. Shredder used a robotic body to assume a human identity and created the Foot Clan. He ruled the entire Japan at that time but the other utroms fought him and he lost control of Japan. Centuries later, Shredder goes to america and turn the Foot Clan into a criminal empire, employing street gangs to do his bidding.

Personality
The Shredder is cruel, ruthless, and never tolerates failures.

In the 1987 cartoon, he was a more comic villain, but evil nonetheless.