Tim O'Brien may refer to:

• Tim O'Brien (author) (born 1946), American author
• Timothy O'Brien (endocrinologist), Irish professor
• Timothy L. O'Brien (born 1961), American journalist
• Tim O'Brien (musician) (born 1954), American musician
• Sir Tim O'Brien, 3rd Baronet (1861-1948), Irish-born cricketer
• Tim O'Brien (politician) (born 1968), legislator in the Connecticut House of Representatives
• Tim O'Brien (illustrator) (born 1964), American artist
• Timothy O'Brien (theatre designer) (born 1929), British theatre designer

[ Source: Wikipedia ]