Federal & State Judges
254 judges — Article III appointments from the Federal Judicial Center directory.
John Watkins OliverChief JudgeMissouri Western District Court · 1962–1990- Ralph A. Oliver1938–1962
- Robert H. Oliver1998–2015
- Rozella A. Oliver
Solomon Oliver Jr.Chief JudgeOhio Northern District Court · 1994–present
Vernon Dion OliverCurrently servingConnecticut District Court · 2023–present
Webster J. OliverChief JudgeUnited States Court of International Trade · 1940–1969- Elizabeth Ufkes Olivera2010–2019
- Charlaine F. OlmedoCurrently serving2002–present
- Mario G. Olmos1983–1990
- Garrett W. Olney1998–2007
- Warren OlneyCalifornia Supreme Court · 1919–1921
- Emily OlshanskyCurrently serving2004–present
- Culbert Levy Olson
- Gregory Jerome OlsonCurrently serving2018–present
- John K. Olson2006–2020
- Judith Ference OlsonCurrently serving2010–present
- Julius J. Olson1934–1948
Justin Ross OlsonCurrently servingIndiana Southern District Court · 2026–present- Lester E. Olson1966–1985
- Lynn Diane OlsonCurrently serving2007–present
- Ralph O. Olson1951–1955
- Robert M. Olson1972–1995
- Graciela Olvera2013–2014
Jose Rolando Olvera Jr.Currently servingTexas Southern District Court · 2015–present
Kathleen McDonald O'MalleyCurrently servingFederal Circuit Clerk/Executive · 1994–present- Martin J. O'Malley1943–1949
- Mary Ann O'Malley2009–2010
- William A. O'Malley1985–2006
- LaFel Earl Oman1971–1977
John Corbett O'MearaMichigan Eastern District Court · 1994–2024- Robert S. Ondrovic2021–2034
- Cecil Talmadge O'Neal1949–1955
- John Belton O'Neall1859–1863
- Stephen E. O'Neil1989–2001
- C William O'Neill1960–1978
- Harriet O'Neill1999–2010
Lawrence Joseph O'NeillChief JudgeCalifornia Eastern District Court · 1990–present- Robert F. O'NeillCurrently serving1999–present
- Thomas Newman O'Neill Jr.Pennsylvania Eastern District Court · 1983–2018
- Vincent J., Jr. O'Neill2011–2012
- William Michael O'NeillCurrently serving2013–present
- Kelly O'Neill Levy2013–2916
- Tomson Tio OngCurrently serving2000–present
- Rafael Astraquill OngkekoCurrently serving2002–present
- Charles Austin O'NIELL1914–1949
- John Frank Onion jr1967–1988
- Marian P. Opala1978–2010
- Robert N. Opel 2Currently serving2006–present
- Peter A. Oppeneer
- Reuben OppenheimerCourt of Appeals of Maryland · 1964–1967
- Clarence V. Opper1938–1965
- Daniel S. OppermanCurrently serving2006–present
- James R. Oppliger2003–2010
- Gail Angela O'RaneCurrently serving2013–present
- Scott Oravec
- Charlotte J. OrcuttCurrently serving2005–present
- James OrensteinCurrently serving
- Adrienne A. Orfield1998–2020
- Franklin B. Orfield1969–1988
- Michael B. Orfield1998–2009
- Melvin Orfinger1979–1989
- Richard OrfingerCurrently serving2000–present
- Tiffany E. Organ-BowlesCurrently serving2017–present
Stephen Murray OrlofskyNew Jersey District Court · 1995–2003- Gregory K. OrmeCurrently serving1987–present
- Peter E. Ormsby
- William M. Ormsby
- George Orndoff2001–2013
- Lawrence Edward OrnellCurrently serving2013–present
- Delbert William OrosCurrently serving2007–present
- James Francis Xavier O'Rourke
- John G. O'Rourke2001–2003
- Terry Byron O'Rourke1984–1998
- Gary Rico OrozcoCurrently serving2001–present
- Patricia A. OrozcoCurrently serving2004–present
- Yolanda OrozcoCurrently serving2010–present
Charles Prentiss OrrPennsylvania Western District Court · 1909–1922- Joseph A. Orr1998–2001
- Mark E. Orr2006–2014
- Robert F. Orr1986–2004
- Warren H. Orr1930–1939
William Edwin OrrNinth Circuit Court of Appeals · 1939–1965
William Horsley Orrick IIICalifornia Northern District Court · 2013–present
William Horsley Orrick Jr.California Northern District Court · 1974–2003
Matthew Emile OrsoCurrently servingNorth Carolina Western District Court · 2025–present- Darleen OrtegaCurrently serving2003–present
- Reuben A. Ortega1984–1988
- Charles E. Orth jrCourt of Appeals of Maryland · 1976–1980
- Revius Ortique jr1993–1994
- Elia Ortiz2012–2019
- Andrew L. Osborn1871–1875
- Walter , Jr. Osborn1965–1983
- Earl T. Osborne1967–1975
- Edwin M. Osborne1986–1994
- Leslie Lester Osborne2019–2024
Diarmuid Fionntain O'ScannlainNinth Circuit Court of Appeals · 1986–present- Eugene Osko
- Benny C. Osorio2008–2018
- Thomas J. OsowikCurrently serving2007–present