Michael T. O'Brien (born 1949 or 1950) is an American former labor union leader.
O'Brien worked as a school bus driver in Bristol Township, Pennsylvania from 1972, joining the Transport Workers Union of America (TWU).
In 1983, he began working full-time for the international union, as an organizer, and immediately began organizing workers at what became American Eagle.
In his various posts, he negotiated many contracts, and led a strike of food service workers at Marriott International.
Under his leadership, the union's local 100 led the 2005 New York City transit strike, which O'Brien refused to support.