Mine are:

The End (Sonic)

Bill Cipher (Gravity Falls)

Adam (Neon Genesis Evangelion)

Nakhash (Star Wars)

Morgoth (Middle Earth)

Vecna (Stranger Things)

Dark Danny and Big Jack Horner.

No one.

Though Morgoth, God (Supernatural), Crimson King, and Nakhash are worse. Don't think Palpatine is though.

The scarlet king

@Erdan5 Palpatine is definitely worse than the Devil. He was made to be, actually.

Zamasu, Dimentio, Westcott and Darkseid.

Kyubey