James R. Barton (1810?– January 23, 1857) was the second sheriff of Los Angeles County, California, and the first to die in office, in the line of duty.
Barton and three of his deputies were killed near present-day Irvine, California in a shootout with bandits led by Juan Flores and Pancho Daniel on January 23, 1857.
Harris Newmark described the reception of the bodies and the funeral: ... when the remains were received in Los Angeles on Sunday about noon, the city at once went into mourning.
Flores and another gang member were captured the next day by an El Monte posse led by Frank Gentry, but escaped again that night.
However Flores was later captured in Simi Pass by a detachment of a company of Los Angeles men led by James Thompson, and U. S. soldiers from Fort Tejon.