A member of the Quorum of the Twelve Apostles
, an organization
in The Church of Jesus Christ of Latter-Day Saints
. He is, in short, a cool guy
He was actually a Lawyer and a Judge before being called to the apostleship. In 1984, he was a leading candidate for a vacancy on the United States' Supreme Court, already being a a member of the Utah Supreme Court. However, right about that time, he was called to be an apostle, and decided that was the more important job for him to hold.
He was also president of Brigham Young University from 1971 to 1980.
I'm getting most of my information from the church magazine articles from www.lds.org, which is a very convenient thing.
There's a good article on him in the Liahona. (Liahona/1985/Tambuli October-November 1985 /Elder Dallin H. Oaks: In the Footsteps of the Other Apostles). At this point, I'm just going to blockquote a relevant paragraph:
Elder Oaks was born in Provo, Utah, 12 August 1932, and grew up a worker. He began working for pay only three or four years after his father died, to help his widowed mother. Dr. Lloyd Oaks’ death (of tuberculosis) left his young widow Stella with three children: Dallin, eight at the time, and the oldest; Merrill, now a Provo, Utah, ophthalmologist; and Evelyn, now Mrs. H. Ross Hammond, of Salt Lake City.
There's tons more information on Elder Oaks, of course, but I'm not going to spam anymore. It's fairly easy to look up.