James Pendleton Vandiver (1869–1932) was a Kentucky fiddler, born there shortly after the American Civil War.^[1] He was the uncle to bluegrass musician Bill Monroe, who immortalized him in a song, "Uncle Pen".^[2]

Monroe used to hear his uncle playing fiddle on the hilltop where he lived, while Monroe put away his mules at night.^[1] He later said that Vandiver was "the fellow that I learned how to play from."^[2] Vandiver played fiddle at local square dances and social events, and his nephew backed him up, playing mandolin.^[1] Monroe's parents had both died by the time he was 16, and he lived part of the time with his Uncle Pen, in his two-room hilltop house in Rosine, Kentucky.^[2] Vandiver had been crippled earlier, and he made some money with his music.^[1] Bill Monroe's biographer, Richard D. Smith writes, "Pen gave Bill more: a repertoire of tunes that sank into Bill's aurally trained memory and a sense of rhythm that seeped into his bones. Sometimes Bill played guitar behind his uncle, sometimes the mandolin."^[3]

On September 13, 1973, a monument in honor of Uncle Pen was unveiled by Monroe at the Rosine Cemetery.^[4] Another way he honored Penn's memory was to play the part of "Uncle Penn" in Ricky Skaggs' Country Boy music video.