Daniel Peter O'Brien (born 1971) is an American baseball coach who currently works in the player development department of the San Francisco Giants organization.

[2][3][4] O'Brien played at UC San Diego, led the team in home runs, continues to rank highly on several career lists.

In his first year, he helped the team to a third-place finish in the NCAA Division III Baseball Championship.

After three seasons, the Tritons moved the program to Division II, joining the California Collegiate Athletic Association.

O'Brien helped establish the Tritons as a strong program in the CCAA, leading them to the College World Series in consecutive years, finishing third and second in 2009 and 2010, respectively.