Sampson, a Native American Muscogee (Creek), was born in Hitchita, Oklahoma. Sampson's most notable roles were as "Chief Bromden" in One Flew Over the Cuckoo's Nest and as "Taylor the Medicine Man" in the horror film Poltergeist II. He had a recurring role on the TV series Vega$, as Harlon Twoleaf and starred in the movies Fish Hawk, The Outlaw Josey Wales and Orca.
Sampson also appeared in the production of Black Elk Speaks with the American Indian Theater Company in Tulsa, Oklahoma where David Carradine and other Native American actors like Wes Studi and Randolph Mantooth starred in stage productions.
In need of a heart and liver transplant, he died on June 3, 1987 of post-operative kidney failure and pre-operative malnutrition problems. Will was 53 years old. He was buried in Hitchita's Graves Creek Cemetery.