Who said "There's nothing to fear but fear itself."?

This quote is attributed to Scooby-Doo.

There's nothing to fear but fear itself. - Scooby-Doo

"There's nothing to fear but fear itself."

Scooby-Doo Courage

"Scooby-Dooby-Doo, where are you?"

"Ruh-roh!"

"Like, zoinks!"

"Let's split up, gang!"

"Never let fear stop you from chasing your dreams."

"Courage is being afraid but doing it anyway."

"Sometimes you gotta do what you gotta do."

"Sometimes you have to be the monster to stop the monsters."