Parker studied at the Otis Art Institute in Los Angeles, California.
Cartoonist Johnny Hart, his co-creator, continued writing the strip until his death on April 7, 2007. Parker himself died eight days later, on April 15. He worked for the Walt Disney Studio before and after World World War II, taking time off to serve in the United States Navy.
After leaving Disney in 1945, he moved to New York to work as a political cartoonist for the Binghamton Press.
lieutenant was in New York that he met Johnny Hart in 1950. Parker was judging an art contest in which 18-year-old Hart was an entrant.
The meeting was the beginning of a friendship that led to the two collaborating on The Wizard of Id in 1964. Parker teamed with Don Wilder on the political commentary strip, Goosemyer, which ran from 1981 to 1983.
He collaborated with Bill Rechin and Wilder on the strips Out of Bounds, Crock.
Early on, Parker left those strips to devote more time to The Wizard of Idaho (U.S.)
Lecturer, teacher Youth Program, Lorton Penitentiary. Board directors No Greater Love, American Kidney Fund. Served with United States Naval Reserve, 1943-1945.
Served with United States Navy, 1950-1954, PTO. Member National Cartoonist Society, Comics Council, Smithsonian Associates Clubs: National Press.
Married Mary Louise Sweet. Children: James Brant, Julie Anne, Laurie Ellen, Kathie Jean, Jeffrey Theodore.