Sansom was born in Salt Lake City on April 2, 1927. He graduated from East High School in 1944 and immediately joined the Navy, serving just short of a year during World War II before joining the reserves. He briefly attended the University of Utah, then went to Brigham Young University, receiving a degree in broadcasting in 1949. He was called up for Navy service during the Korean War and entertained troops with the United Service Organizations.
Sansom took his talent for mimicry to radio, on KSL in 1957, with the show "Sansom and Then Some," in which he played the roles of host, guest and caller. He moved to Los Angeles in 1968 to begin a career in movies and television, landing roles in movies such as The Sting, Herbie Rides Again, Airport 1975 and Funny Lady, as well as a slew of guest roles on TV and cartoon voices.
In 1976 he joined DAYS OF OUR LIVES as Dr. Frederick Powell.
Starting in 1988, Sansom took on his best-known role, as the fretful Rabbit in Disney’s "Winnie the Pooh" animated films and TV shows. (Disney’s original Rabbit, Junius Matthews, died in 1978.) Sansom played Rabbit, forever vexed by the honey-hungry Pooh and the rambunctious Tigger, for 22 years. He continued recording Rabbit from Utah studios when he moved back home to Salt Lake City in 1992. The role was taken over by Tom Kenny, the voice of SpongeBob SquarePants, for the 2011 movie "Winnie the Pooh."
Sansom is survived by his wife, Carla, whom he married in 1961; three children, Matthias, Melanie and Melissa; nine grandchildren and 16 great-grandchildren.