Browse Fellows - O
- Oakden, William Marshall (1886 - 1928), General surgeon and Orthopaedic surgeon
- Obré, Henry ( - 1867), General surgeon and Ophthalmic surgeon
- O'Brien, Peter (1806 - 1882), General surgeon
- O'Connor, Thomas (1813 - 1896), General surgeon
- Odell, William (1851 - 1925), General surgeon and Physician
- O'Donnell, Henry (1813 - 1870), General surgeon and Ophthalmic surgeon
- O'Donoghue, Patrick Desmond (1922 - 2004), General surgeon
- Ogg, Archibald John (1921 - 2005), Ophthalmic surgeon
- Ogilvie, Fergus Monteith (1862 - 1918), Ophthalmic surgeon
- Ogilvy, Alexander (1769 - 1846), General surgeon
- O'Keeffe, Declan (1922 - 2005), General surgeon
- Okes, John (1793 - 1870), General surgeon
- Oldham, Charles James (1845? - 1907), Ophthalmic surgeon
- Oldham, James (1817 - 1881), General surgeon
- Oldham, Riton ( - 1881), General surgeon
- Oliver, Matthew William Baillie (1882 - 1926), Ophthalmic surgeon
- Oliver, Richard Hywel Picton ( - 2010), General surgeon
- Ollier, Louis Xavier Édouard Léopold (1830 - 1900), General surgeon
- O'Malley, Eoin (1919 - 2007), Cardiac surgeon
- Ommaya, Ayub Khan (1930 - 2008), Neurosurgeon
- O'Neill, Thomas (1912 - 2000), General surgeon
- Ong, Guan Bee (1921 - 2004), General surgeon
- Onyeaso, Onyemara Nduche, General surgeon
- Openshaw, Thomas (1856 - 1929), Orthopaedic surgeon
- Ord, George (1803 - 1886), General surgeon
- O'Reilly, James Alphonsus (1925 - 2008), ENT surgeon
- Organ, Claude H (1927 - 2005), General surgeon
- O'Riordan, Sean Michael (1944 - 2006), Orthopaedic surgeon
- Ormerod, William Piers (1818 - 1860), General surgeon
- Ormrod, John Neville (1922 - 2009), Ophthalmic surgeon
- Orr, Neil Wallace Morison ( - 2012), General surgeon
- Orr, Wilbert McNeill (1930 - 2008), General surgeon and Transplant surgeon
- Orsborn, John ( - 1883), General surgeon
- Orton, George Hunt (1842 - 1920), General surgeon
- Orton, Peggy Kathleen Lillian (1914 - 2009), ENT surgeon
- Osborn, Samuel (1814 - 1869), General surgeon
- Osborne, David Robert (1943 - 2008), Urological surgeon
- O'Shaughnessy, Richard (1812 - 1889), General surgeon
- Osung, Okon Akpan ( - 2010), General surgeon
- Otley, John (1809 - 1875), General surgeon
- Ottaway, James Cuthbert ( - 1891), General surgeon
- Ottley, Walter (1850 - 1883), Anatomist and General surgeon
- Otway, Charles William Carrol (1816 - 1879), General surgeon
- Ouston, Thomas George (1869 - 1911), ENT surgeon and General surgeon
- Overend, Wilson (1806 - 1865), General surgeon
- Owen, Anthony Wynn Michael Carton ( - 2012), oncologist
- Owen, Edmund Blackett (1847 - 1915), General surgeon
- Owen, Edward Robert (1809 - 1880), General surgeon
- Owen, Edwin Nicholas ( - 2005), ENT surgeon
- Owen, Harvey Kimpton (1816 - 1886), General surgeon
- Owen, Sir Richard (1804 - 1892), Anatomist and Curator
- Owen, William Jones (1945 - 2003), General surgeon
- Owen, William Mervyn ( - 2005), ENT surgeon
- Owen-Smith, Bertram (1922 - 2008), Plastic surgeon and Politician
- Oxley, Robert (1806 - 1891), General surgeon