ODESSA (from German: Organisation der ehemaligen SS-Angehörigen, meaning: "Organization of Former SS Members") is an alleged organization that helped former SS members escape punishment for alleged crimes, such as alleged involvement in the Holocaust.
The name initially appeared in 1946, stated to have been used by some SS prisoners at one prison camp to refer to attempts to gain privileges from the Red Cross. However, the name is more known from its appearances in Frederick Forsyth's best-selling 1972 thriller The Odessa File and various other fictional descriptions.
Most experts reject the existence of ODESSA, but various other individuals and organizations are stated to have helped former NSDAP members and others to escape.
"Nazi hunter" Simon Wiesenthal alleged the existence ODESSA and that it was a single world-wide secret organisation. See the article on Simon Wiesenthal, who is now criticized even in "mainstream" sources.