Johnnie Harron, a younger brother of silent screen star Robert Harron, was born on March 31, 1903, in New York City. He initially gained exposure to the film industry by making an unbilled appearance in his brother's film, Hearts of the World, in 1918.
Following his brother's sudden and mysterious death in 1920, which was listed as accidental but some believed might have been suicide, John was essentially handed a movie career on a silver platter. He took over his brother's role as a young, innocent, and wholesome romantic lead opposite silent screen's top femme stars, effortlessly coasting through hundreds of films.
Although he showed significant promise in films such as The $5 Baby, The Ragged Heiress, Dulcy, My Wife and I, The Boy Friend, and Silk Stockings, he never managed to achieve the same level of fame as his brother. By the time sound became a major aspect of filmmaking, John had been relegated to bit and unbilled parts in second-string films.
After completing location work on his final picture, John returned home feeling unusually exhausted. He traveled to Seattle for some fishing and rest, but soon developed a severe headache and was hospitalized. He was diagnosed with spinal meningitis and tragically passed away on November 24, 1939, at the age of 36. John was survived by his wife, actress Betty Westmore, and their young daughter, Colleene.