James Greenwood Sr. (1878-1949), and James Greenwood Jr. (1907-1993) were a father and son who practiced neuropsychiatry and neurosurgery, respectively, for many years in Houston, Texas. While usually identified by the suffixes of Sr. and Jr., James Greenwood Sr. sometimes was identified as James Greenwood, Jr., as his father was James Greenwood (1851-1925) of Seguin, Texas.

James Greenwood Sr. was born April 18, 1878, in Seguin, Texas to James and Corinna (Henderson) Greenwood. He graduated from University of Texas Medical Branch (UTMB) Galveston in 1901 and began practice in Seguin. From 1902 to 1906 he was on the staff of the San Antonio State Hospital for Mental Diseases. From 1906 to 1908 he maintained a private practice in Seguin, Texas. From 1908 to 1912 he served on the faculty of the Department of Medicine at UTMB Galveston. In 1912 he opened the Greenwood Sanitarium for the treatment of neuropsychiatry diseases in Houston, Texas, located northwest of the current intersection of Fannin St and Old Spanish Trail, and continued its operation until his retirement in 1947. He was also the first Chairman of the Department of Neuropsychiatry at the Baylor University School of Medicine in Houston. He died August 22, 1949, in Houston, Texas.