Interesting: There were 12 doctors in Tombstone in the 1880s, and Goodfellow was one of only 4 that actually had a medical degree... (Clearly, you paid your money and took your chances.)
He was a stand up guy, fearlessly allied with the Earps against the "cowboy" faction, and treated both Virgil and Morgan when they were wounded at the OK Corral, Virgil again when he was maimed in a shotgun ambush on Allen Street, and Morgan again when he was shot in the back at Hatch's Saloon.
When Luke Short killed Charlie Storms in 1881, Doc Goodfellow did the autopsy. He
found that while Storms had been shot in the heart, the bullet lodged there rather than exiting out the back, and he was intrigued to find the slug encased in silk from a pocket handkerchief. Between this incident and another, where a silk neckerchief was found to have stopped a bullet in a cowboy's neck, Goodfellow got interested in the bullet stopping properties of silk, and became a pioneer experimenter in the making of bullet proof vests. In 1887 he published a paper titled, Notes on the Impenetrability of Silk to Bullets.
Oh... the President of Mexico, Porfirio Diaz, gave him that horse.