John Clayton VanOrnum (born October 20, 1939, at Pasadena, California) is an American former professional baseball player, manager, coach and scout. From through , VanOrnum served as the bullpen coach of the San Francisco Giants of Major League Baseball.
Primarily a catcher during his six-year minor league playing career (1959–64), he was a member of the Los Angeles Dodgers and Los Angeles Angels organizations, then managed in the Giants' farm system at the Class A and Double-A levels from 1973 to 1978. He threw and batted right-handed, and stood tall and weighed .
After his term as a Giants' coach under Dave Bristol, Frank Robinson and Danny Ozark, VanOrnum then worked as a Major League and advance scout for the Giants, Dodgers, Angels and Atlanta Braves through .
Early in his playing career, VanOrnum served as the catcher on the 1959–60 television series Home Run Derby, which was filmed at Los Angeles' Wrigley Field.