Onorato Timothy O'Meara (January 29, 1928 – June 17, 2018) was an American mathematician known for his work in number theory, linear groups and quadratic forms.
O'Meara was born in South Africa and graduated from University of Cape Town in 1947.
He continued there for a master's degree, then transferring to Princeton University where he obtained the Ph.D. in mathematics in 1953.
Subsequently he returned to New Jersey and was in the Institute for Advanced Study.
In 2008, the University of Notre Dame Mathematics Library was rededicated and named in O'Meara's honor.