John Barclay Armstrong (January 1, 1850 – May 1, 1913) was a Texas Ranger lieutenant and a United States Marshal, usually remembered for his role in the pursuit and capture of the famous gunfighter John Wesley Hardin. Armstrong resigned his position at the Rangers in 1881, and was shortly after appointed U.S. Marshal.

He established in Willacy County, Texas, where he founded a considerably large ranch. He died at his home in Armstrong, Texas, on May 1, 1913