- O'Brien, Dr. William A. (2)
- O'Brien, Dr. William Jr. (1)
- O'Brien, William A. (1)
- O'Brien, William Austin (1)
- O'Connell, Brian (1)
- O'Conner, William Van (2)
- O'Connor, Kathy (1)
- O'Meara, James (1)
- O'Neil, Mary (1)
- O'Shaughnessy, Margaret (1)
- O'Steen, David (1)
- OVerdahl, Curtis (1)
- Oberstar, James (1)
- Ode, Sigurd Q. (2)
- Odegaard, Robert (1)
- Ogdahl, Harmon (2)
- Ohrt, Del (2)
- Oldendorf, Yvette (2)
- Oldendorf, Yvette (State Coordinator of the DFL Feminist Caucus) (1)
- Oleisky, Allen (1)
