Though their exact origins are a mystery, it is obvious that they are hideously mutated ninja that wear armor similar to The Shredder. The Shredder Clones consist of a large, four-armed Shredder (known as Multi-Arm Shredder in toy form, and Shiva Shredder on 4Kids' website), one with large, monstrous crustacean-like claws (known as Claw Shredder in toy form, and Spike-Armed Shredder on 4Kids' website), and a diminutive Shredder with a single, long wrist blade on each arm (called Mini Shredder on 4Kids' website).
In the 2003 TV series they are introduced at the end of Episode 21, "Return to New York, Part 1", the Shredder Clones are seen in liquid-filled vats deep within Foot Headquarters. The Shredder Elite are released when an alarm goes off shortly after the Turtles and Splinter arrive. In the following episode, The Turtles and Splinter battle them. Their appearance has changed slightly to more closely resemble this universe's version of The Shredder, and the "Spike-Armed Shredder"'s claws are less crustacean-like in appearance. Spike-Armed Shredder was last seen coming out of a pile of rubble. Shiva and Mini Shredder were last seen on top of an elevator as it was falling. None of their fates are known.
The trio's origins in this series are more obscure; Donatello and Michelangelo refer to them as clones, this however could not be true, as The Shredder is later revealed to be the Utrom Ch'rell (the episode synopsis on ninjaturtles.com confirms they are not clones). Though the action figures and 4Kids blog refer to them as clones. There maybe a possibility that they were forged from the original human Oroku Saki that Ch'rell had somehow taken DNA samples from a long time ago and used them later on in the present to create the Shredder Clones.
2003 saw the release of figures of both Claw Shredder and Multi-Arm Shredder, designed after the versions of the characters seen in the 2003 series. A Mini-Mutant version of Multi-Arm Shredder was released in 2008, packaged with Extreme Sports Raphael. This version's body and armor are different shades of gray and silver, and is referred to as just "Shredder" on the packaging.