Freeza is a Lizard-type-changling creature. Who is one of the most feared powers in the universe. Freeza consist of total evil and wants to control all and if it can't be controlled he'll destroy it. Freeza is first introduced as a tyrant who ruled over the saiya-jins. How he first came to meet up with them was like this. Freeza who was constantly taking over planets and had a huge enormous army of followers. One day Freeza observed the saiya-jins taking over a planet and selling it to other aliens to make money. Freeza thought that there talents would come in useful in his attempt to rule all. Freeza offered the saiya-jins a life of luxury for exchange for them to destroy planets in the name of Freeza. So all the saiya-jins had to do is go fight on different planets, which they loved to do, so they thought, hey how could we lose. King Vegeta was sick of Freeza ruling them and became outraged when freeza wanted to take his son. So King Vegeta planned an attack on Freeza, which failed and cost him his life. As sometime went on King Vegeta son grew into a great fighter even at his very young age. So Zarbon thought the saiya-jins could be trouble if they bonded together so Freeza decided to destroy Planet Vegita and all it's inhabitats.
Freeza is beaten when SSJ Gokou tricks him into slicing himself inhalf, then letting him blow up on planet namek. He later resurfaces as Cyborg Freeza and is killed by Trunks when he slices him into a million little pieces and then blast away the pieces.
Cell is supposed to be the ultimate android created by Dr. Gero, a great scientist. Cell was given the Cells (hence the name Cell) of the greatest fighters which include: Gokou, Freeza, Vegeta, Piccolo, King Cold and more. He was created in an underground labortory and the process continue despite #17 and #18 attempts to destroy the lab. Once the process finished Cell needed to absorb #17 and #18 to become Perfect Cell, but Trunks already killed them both when returning from the past. So Cell killed Trunks and went into his time machine. In order to fit in he had to change into an eariler version of himself. Once in the present timeline he dug himself into the ground in order to grow back to his normal state. Cell later finds #17 and #18 and absorbs them to become Perfect Cell. With the saiya-jins love to fight in his blood, he challenges all the best fighters on earth to the ultimate martial arts competition.
Perfect Cell is defeated when SSJ2 Gohan beats the crap out of him and in a last attempt to destroy everyone, Cell begins to self destruct until Son Gokou teleports them both to Kaio-sama's planet, leading to both of there destruction.
Later Cell reformed due to the fact that they didn't destroy his main system that keeps him alive. So Cell reformed as the Absolute Perfect Cell. Gohan then beats Cell with a one arm Kamehameha with the help of Vegeta, courage from Gokou and support from the rest of the z-team.
