Ronald Charles McKernan (September 8, 1945 - March 8, 1973), known as Pigpen, was an American singer and musician. He was a founding member of the San Francisco band the Grateful Dead and played in the group from 1965 to 1972. McKernan grew up heavily influenced by African-American music, particularly the blues, and enjoyed listening to his father's collection of records and taught himself how to play harmonica and piano. He began socializing around the San Francisco Bay Area, becoming friends with Jerry Garcia.

McKernan was close friends with American singer-songwriter Janis Joplin due to common musical influences and lifestyles, particularly a shared love of alcohol over other drugs; a poster from the early 1970s showed them together at 710 Ashbury. Joplin joined McKernan on stage at the Fillmore West on June 7, 1969, with the Grateful Dead to sing his signature "Turn On Your Love Light," reprising this duet on July 16, 1970, at the Euphoria Ballroom in San Rafael, California.  He developed a close friendship with fellow keyboardist Tom Constanten based on their mutual aversion to psychedelics and eventually served as best man at Constanten's first wedding. While his bandmates and friends were using cannabis, LSD, and other hallucinogenic drugs, McKernan preferred alcoholic beverages such as Thunderbird and Southern Comfort. Ironically, McKernan was arrested and fined after the cannabis bust on November 9, 1967, at 710 Ashbury Street, the Dead's communal home, even though he did not use the drug. The event was covered in the first issue of Rolling Stone, where the reporter noted McKernan had a substantial rifle collection and McKernan's picture appeared on a contemporary report in the San Francisco Chronicle. Because neither took illegal drugs, McKernan and Constanten were the only members of the band not arrested on the January 31, 1970, bust that inspired the lyrics of the band's song "Truckin'".  In the early years of the Grateful Dead, McKernan was easily recognisable by his biker image, making him a minor celebrity. In 1969, the band's record company, Warner Bros., ran a "Pigpen Look-Alike Contest".

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eventually served as best man at Constanten's first wedding.