Doolin was born on a farm near Tulsa, Oklahoma. He drifted west starting at age 23, eventually ending up in Caldwell, Kansas. He was hired by cattleman Oscar D. Halsell, a Texas native, and began working for Halsell as a cowboy in Oklahoma. During this time, he worked with other noted cowboy/outlaw names of the day, including George "Bitter Creek" Newcomb, Charlie Pierce, Bill Power, Dick Broadwell, Bill "Tulsa Jack" Blake, Dan "Dynamite Dick" Clifton, and Emmett Dalton.
