Can we talk about how Cell's first form is literally the boogeyman? While Frieza is the best villain because of his history, Imperfect Cell was by far the most menacing.
Just the whole concept of him would make a frightening horror movie. He's this gigantic insectoid looking thing that creeps around in the shadows and targets the everyday person. He didn't kill people by simply blowing them up either. He stabbed you with his tail and sucked your organs dry from the inside out, leaving nothing but your clothes scattered on the floor
I'll never forget that first scene of him absorbing someone in front of Piccolo. Piccolo was absolutely terrified
Then there were the scenes of empty towns littered with only the clothed remains of people Cell killed. Or those scenes where he became a slasher movie villian like when he impaled that couple with his tail at a carnaval. Looking back I'm surprised they didn't put DBZ on the Adult Swim block because of the way he killed people