O'Brien

O'Brien could refer to:


 * Miles O'Brien, transporter chief aboard the USS Enterprise-D, and Chief of Operations aboard Deep Space 9
 * Miles O'Brien (mirror), the mirror universe version, also known as "Smiley"
 * Miles O'Brien (replicant), a replicant created by the Parada government
 * Keiko O'Brien, biologist and wife to Miles O'Brien
 * Molly O'Brien, first child of Miles and Keiko O'Brien
 * Kirayoshi O'Brien, second child of Miles and Keiko O'Brien
 * Michael O'Brien, father of Miles O'Brien
 * Miranda O'Brien, an alternate timeline descendant of Miles O'Brien
 * Sean Aloysius O'Brien, labor union leader in the 20th century, and ancestor to Miles O'Brien
 * O'Brien family, the family unit that Miles and Keiko belong to
 * O'Brien, a character in the Dixon Hill stories

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