How about

George Washington
Thomas Jefferson
James Madison
Ben Franklin
Carl Sagin
George Carlin
Richard Pryor
The Beatles
Bob Dylan
Stacy Keach
Louis Armstrong
Robert Mitchum
Tom Petty
Michelle Phillips
Cypress Hill
The Buddha
Zoroaster
Jesus

Just to name a few of the hardcore stoners.

I bet there are very few celebrities who are alive today who haven't toked at least once, even if they didn't know how to inhale.