Who said "The scariest monsters are created by lies and secrets."?

This quote is attributed to Scooby-Doo.

The scariest monsters are created by lies and secrets. - Scooby-Doo

"The scariest monsters are created by lies and secrets."

Scooby-Doo Truth

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

"Ruh-roh!"

"Like, zoinks!"

"Let's split up, gang!"

"Lucy, you got some 'splainin' to do!"

"You must always be honest with the people you love."

"Truth always comes out in the end."

"Honesty is always the best policy."