Who said "Fear is the most powerful weapon."?

This quote is attributed to Palpatine.

Fear is the most powerful weapon. - Palpatine

"Fear is the most powerful weapon."

Palpatine Fear

"Did you ever hear the tragedy of Darth Plagueis the Wise?"

"The dark side of the Force is a pathway to many abilities some consider to be unnatural."

"Have you ever heard of the tragedy of Darth Plagueis? I thought not."

"Unlimited power!"

"Face your fears with courage."

"You can't live your life in fear."

"Snakes. Why'd it have to be snakes?"

"Fear is just another obstacle to overcome."