| Ian Brady | 1963 - 1965 | United Kingdom | 5 |
| Ian Kevin Huntley | 2002 | United Kingdom | 2 |
| Idella Kathleen Hagen | 2000 | USA | 2 |
| Idoia López Riaño | 1984 - 1986 | Spain | 23 |
| Idris Abdus-Salaam | 2020 | USA | 3 |
| Ignacio Cuevas | 1974 | USA | 1 |
| Igor Alexandrovich Mirenkov | 1990 - 1993 | Soviet Union | 6 |
| Ilpo Tapio Larha | 1992 | Finland | 1 |
| Imam Samudra | 2000 - 2002 | Indonesia | 202 |
| Imre Arakas | 1979 - 2023 | Estonia | 1+ |
| Inessa Tarverdiyeva | 2007 - 2013 | Russia | 30+ |
| Ioan Balaban | 1948 - 1953 | Australia | 5 |
| Ion Rîmaru | 1970 - 1971 | Romania | 4+ |
| Iouri Gherman Mikhel | 2001 - 2002 | USA | 5 |
| Ira Samuel Einhorn | 1977 | USA | 1 |
| Irene Leidolf | 1983 - 1989 | Austria | 5 |
| Irene Schroeder | 1929 | USA | 1 |
| Irina Viktorovna Gaidamachuk | 2002 - 2010 | Russia | 17 |
| Isaac L. Wood | 1855 | USA | 2-3 |
| Isauro Aguirre | 2013 | USA | 1+ |
| Iskandar bin Rahmat | 2013 | Singapore | 2 |
| Israel Keyes | 1996 - 2012 | USA | 3+ |
| Itzcoatl Misael Ocampo | 2011 - 2012 | USA | 6+ |
| Ivan Abner Cantu | 2000 | USA | 2 |
| Ivan Jerome Hill | 1986 - 1994 | USA | 9+ |
| Iván Jesús Arancibia Navarro | 1999 | Chile | 3 |
| Ivan Lee Page | 1998 - 2001 | USA | 3 |
| Ivan Robert Marko Milat | 1989 - 1992 | Australia | 7+ |
| Iwao Hakamata | 1966 | Japan | 4 |
