Cell

" You, Gohan, you tried to kill me but you failed see, I was in Hell during the chaos but I escaped! I was free but damaged so then I was transported to the Big Gete Star where I was reborn! "

— Cell explaining to Gohan how he survived,  reminiscent  of Meta-Cooler

Cell (セル) appears in Dragon Ball Z, Dragon Ball GT, Dragon Ball Z Kai, Dragon Ball Z: A Perfect Resurrection & Dragon Ball Z: Shenron Rises

Pre-Evil Reborn
Even after self-destructing at King Kai's planet, one single cell survives the explosion due to the fact that his design provided for such. Using the regenerative abilities he inherited from Piccolo, Cell is able to completely recover. His cells also retain a memory of his Perfect Form, allowing him to regenerate into that form again despite his loss of both the Androids at this point (Android 17 is also killed in the explosion of Cell's Semi-Perfect body). Due to his Saiyan trait of extreme power increase after healing from injury, he becomes much stronger than he previously is in his Perfect Form, even at full power or when buffed up. Apparently, Cell himself is previously unaware of this ability, as he is shocked that he is still alive. Only then does he fully grasp what Dr. Gero meant by the perfect being.

Using Instant Transmission (acquired from Goku), Cell returns to Earth, kills Future Trunks with the Full Power Death Beam, and explains how he survived. Enraged, Vegeta blindly rushes at him in his Super Saiyan form, but is slapped aside, later, Cell attacks Gohan and due to the sheer power of the attack and the fact that he is unable to actually defend against it, Gohan is left without the use of his left arm and his ki supply reduced to less than half. Cell then wickedly reveals that he will destroy the Earth and then use the Instant Transmission to teleport to various planets in order to destroy each one in the process. The whole situation crushes Gohan's will to fight, convincing him he no longer has the power to defeat Cell.

However, Gohan is told by Goku that his ki issue is just in his mind, and that he can destroy Cell. Gohan desperately engages Cell in a Kamehameha wave struggle at the behest of the late Goku. At this point, the manga and anime take two slightly different approaches on the clash and, consequently, Super Perfect Cell's power. In the anime, Cell gains the upper hand several times, nearly overwhelming Gohan nonchalantly. The other fighters try to distract Cell by attacking him, but fail as Cell simply flares his aura and knocks them all back. As he is about to finish off Gohan, Vegeta distracts Cell with a surprise blast to the side of his head, being much stronger than the others. Vegeta's blast does what the others failed to do. In the manga, while Cell still gains the upper hand, the only one to get involved is Vegeta, and he only needs to do this once. Regardless of the story however, Gohan catches Cell momentarily off guard thanks to Vegeta, allowing Gohan to draw out all of his power to obliterate Cell completely and end the battle.

A Perfect Resurrection
Cell disguises himself as Piccolo and lures Goku and Vegeta into a strange, dark wasteland where he reveals that Piccolo, Dende & Mr.Popo are being tortured horribly and will soon be killed but Goku in SSJ5 form goes to save them after Gohan hits Cell with a Hyper Masenko.

Goku falls through a trap door to find his Brother, Rensou who beats him but Goku is saved by Tiellin (the fusion of Tien & Krillin).

Cell is also eventually beaten but then we see him talking to Whis, who reveals his true alingment by helping Cell become a Perfect God and expressing his disdain for Earth and Bills, his student.

Shenron Rises
Cell with the aid of Bottro or as she was newly deemed, Android 21, Whis and the Gods of Destruction (excluding Bills) defeat the Z-Warriors that consisted of SSJG Vegeta, SSJ9 Goku and Pan & Giru (the parents of Bottro), Whis then proceeds to begin to destroy the Earth, this was a very controversial ending but it was unique.