Who said "I'm the only one who knows that."?

This quote is attributed to Thanos.

I'm the only one who knows that. - Thanos

"I'm the only one who knows that."

Thanos Solitude

"I am inevitable."

"The hardest choices require the strongest wills."

"Perfectly balanced, as all things should be."

"You should have aimed for the head."

"Sometimes being the best means being the loneliest."

"Solitude gives us time to reflect on what matters"

"I'm not good with people, never have been."

"I feel like I'm disappearing."