When O. Henry died in 1910, he was fondly remembered in the magazines. This full page photo showed up in a 1912 issue of Bookman, which I came across recently while looking for something else at google books. Dated 1886, it shows him in the front row (left) as "W. Porter," with three other young men identifying themselves as the "Hill City Quartette."
He would have been a 24-year-old bachelor at the time, living in Austin, Texas. According to Wikipedia: "Porter was a good singer and musician. He played both the guitar and mandolin." The quartet "sang at gatherings and serenaded young women of the town." His writing career was yet to begin.
Coming up: Cy Warman, Frontier Stories (1897)