William O'Brien (American football)
William Edward O'Brien (March 11, 1923 – December 1, 2000) was an American football coach and official. He was the seventh head football coach at the Southern Illinois University Carbondale, serving for three seasons, from 1952 to 1954, and compiling a record of 6–20. O'Brien was an official in the National Football League (NFL) for 18 seasons, from 1967 through 1983, officiating in Super Bowl X in 1976. He wore number 83 for the major part of his NFL career. He was also a professor at Southern Illinois University.
Darby O'Brien
William D. "Darby" O'Brien (September 1, 1863 – June 15, 1893) was a Major League Baseball player in the late 19th century. He played outfield for the New York Metropolitans in 1887 and the Brooklyn Bridegrooms/Grooms from 1888–1892. O'Brien developed lung problems during his playing career and continued to play, despite his ill health. When he reported to spring training for the 1893 season, the team found that he was too ill to play and sent him to Colorado to try to recover. They played a benefit game to raise money for him.