𐌌𐌀𐌃𐌄 𐌁𐌙 𐌔Ꝋ𐌂𐌉𐌄𐌕𐌙 -||- 𐌌𐌄𐌀𐌍𐌕 𐌕Ꝋ 𐌃𐌄𐌔𐌕𐌓Ꝋ𐌙 𐌉𐌕

Mewtwo is an artificial Pokémon. It is a bipedal, humanoid Pokémon with some feline features. Its body is primarily gray with a long, purple tail and a large purple underbelly. On top of its head are two short, blunt, ear-like horns, and it has purple eyes. A tube extends from the back of its skull to the top of its spine, bypassing its neck. It has a defined chest and shoulders, which resemble a breastplate. The three digits on each hand and foot have spherical tips. Its tail is thick at the base but thins before ending in a small bulb.

According to journals found in Kanto's Pokémon Mansion, after discovering the Mythical Pokémon Mew and gathering some of its DNA, Mr. Fuji used it in his mansion to create Mewtwo, a modified clone of Mew with the goal to making it the most powerful Pokémon in existence. It was held and studied in the mansion, where it acquired extreme power and a vicious disposition after enduring horrific gene-splicing experiments. It eventually broke free and fled the mansion, destroying it in the process. In the Pokémon Adventures manga, Mewtwo's creation wasn't possible with the amount of Mew's cells gathered, so to complete it, human cells were used instead, specifically from the Team Rocket scientist Blaine. Due to Blaine possessing some of Mewtwo's cells as well, the two became linked, which granted Blaine to ability to track its whereabouts at the cost of slowly taking his life. Though its DNA is almost the same as Mew's, it is bigger and has a different disposition.

Mewtwo is said to have the most savage heart among all Pokémon, lacking compassion and striking fear into its enemy with cold, glowing eyes. Mewtwo conserves energy by remaining motionless in order to unleash its full power in battle. Because it was engineered to be the ultimate opponent in battle, it can only think of defeating its foes. Though rarely seen in the wild, it is said to be resting in dark caves somewhere. In Mewtwo Strikes Back, Mewtwo was shown to be capable of levitation, mind control, memory erasure, telepathy, teleporting others to another location, and the creation of powerful, world-destroying storms. However, it was later shown to be caring, protective, and even altruistic. As seen in Genesect and the Legend Awakened, Mewtwo can survive in outer space. Mewtwo can transfer a human's soul into a Pokémon provided that said Pokémon is in a crazed state, causing the transferred person to gain control of its body and abilities.