Dan O'Brien, Sr.

Daniel F. O'Brien Sr. (March 26, 1929 – January 16, 2017) was an American front office executive in Major League (MLB) and minor league baseball who served as the general manager of three American League West Division teams. He was the father of Dan O'Brien Jr., a former MLB general manager and scouting director.

Biography
Born in Elizabeth, New Jersey, he was a graduate of Thomas Jefferson High School. O'Brien attended Seton Hall University and graduated from Florida Southern College, where he played varsity baseball and basketball. He served in the United States Army during the Korean War and was discharged in 1954.

O'Brien was a general manager in the minor leagues from 1955–63 in the Pittsburgh Pirates and Milwaukee Braves organizations, then spent another nine years (1964–72) as the chief assistant to Phil Piton and Hank Peters, presidents at the time of the National Association of Professional Baseball Leagues, the minor leagues' governing body.

O'Brien came to the Major Leagues when he joined the Texas Rangers as a vice president during its 1973 season, and was promoted to general manager of the Rangers later that year; he would continue in that post through 1978, although he shared power with co-general manager Eddie Robinson in 1977–78.

In 1979, O'Brien became president of the Seattle Mariners, then in their third year as an American League expansion team, and he added the general manager title to his duties from 1981–83, replacing Lou Gorman. He left Seattle in 1984 and joined the front office of the Cleveland Indians in 1986, working with Peters again as his top assistant from 1987–89.

O'Brien then moved to the California Angels as top aide to general manager Mike Port, and then succeeded Port as the team's GM from the close of the 1991 season through 1993. He was replaced by Whitey Herzog at the end of the '93 campaign.

Of O'Brien's three big-league teams, only the Rangers of the late 1970s experienced sustained success, contending for, but never winning, the championship of the American League West Division. The Mariners climbed to the middle of the pack in the AL West in 1982, then fell into the basement, with 102 losses, in O'Brien's last year. In Anaheim, O'Brien inherited a .500 team, but the Angels lost 90 games in 1992 and 91 games more in its 1993 season.

O'Brien died on January 16, 2017 in Dallas, Texas, at the age of 87.