If you have information regarding the death of an alumni, faculty or staff member, please email Paul Scott at pjscott51@flaget.org or Mark McWhorter at mmcwhorter@iglou.com.
| Last Name | First Name | Class/Role | Date of Death |
|---|---|---|---|
| Norton | Richard Eugene (Ricky) | 1962 | July 24, 2013 |
| Nowacki Jr. | Raymond A. "Ray | 1956 | July 31, 2020 |
| O'Brien | Francis E. | 1963 | May 21, 2017 |
| O'Brien | Michael L. | 1957 | August 12, 2010 |
| O'Brien, C.F.X | Br. John F. "Br.Brice | Brother | November 5, 2015 |
| O'Bryan | Charles Arthur "Charlie | 1969 | February 7, 2023 |
| O'Bryan | Joseph C. | 1950 | December 13, 2012 |
| O'Bryan | Patrick Michael | 1956 | March 13, 2020 |
| O'Bryan | William B. | 1946 | December 18, 2010 |
| O'Connor | Rev. Francis A. | Priest | |
| O'Daniel | James E. | 1964 | |
| O'Dea | William C. "Bill | 1956 | December 10, 2023 |
| O'Donnell, C.F.X. | Br. D. Stephen | Brother | |
| O'Hara | Br. Columbiere | Brother | |
| O'Hara | John L. | 1959 | |
| O'Leary | John C. | 1953 | |
| O'Mara | John L. | 1961 | March 7, 2008 |
| O'Mara | William C. | 1960 | |
| O'Neil | Donald L. | 1960 | |
| O'Reilly | Franklin J. | 1951 | |
| Ober | Walter G. | 1947 | May 6, 2017 |
| Oeswein | Gerald H. | 1955 | July 26, 2008 |
| Oetken | W. Jerry | 1953 | May 25, 2016 |
| Ogles | Robert W | 1957 | October 10, 2023 |
| Oldham | David S. | 1961 | |
| Oldiges | Henry W. | 1948 | August 17, 1993 |
| Olges | Donald Paul | 1971 | March 3, 2024 |
| Olges | John B. | 1955 | |
| Olges | John L. | 1953 | July 24, 2023 |
| Oliver | William J. | 1959 | May 6, 2014 |
| Olmstead | Charles F. | 1951 | December 16, 2004 |
| Olrich | William Anthony | 1953 | May 18, 2003 |
| Oppel | Bertrand E. | 1953 | July 29, 2003 |
| Oppel | George R. | 1950 | |
| Orr | Richard L. | 1956 | |
| Orthober | Thomas William "Tom | 1969 | May 6, 2025 |
| Orthober | William Edward | 1956 | June 26, 2020 |
| Osborne | Edward L. | 1949 | September 30, 2023 |
| Osborne | Hubert J. | 1960 | September 15, 2021 |
| Osborne | Patrick | 1946 | |
| Osborne | Rev. Stanley L. | 1951 | July 16, 2018 |
| Osborne | Robert A. | 1959 | |
| Ostendorf | Edward John | 1946 | February 9, 2000 |
| Osterman | Kirk A. | 1967 | July 9, 1993 |
| Osterman | Joseph G | 1961 | July 25, 2021 |
| Osting | James E. | 1957 | February 20, 2016 |
| Oswald | James H. | 1951 | May 25, 2010 |
| Ott | Donald F. | 1953 | |
| Owens | Michael Whalen | 1961 | October 28, 1998 |
| Owens Jr. | Milton B. | 1959 | October 15, 1988 |