My list would include the following ops:
DOWNFALL/OLYMPIC/CORONET (US plans to invade Jap home islands 1945-46)
ZIPPER (Brit invasion of Malaya Sept. 1945)
ECLIPSE (US plan for airborne drop on Berlin)
KINGFISHER (Australian plan to drop 1st Aust Para Bn into Borneo to liberate remaining Australian and British POWs at Sandakan- vetoed by MacArthur and Blamey)
VULTURE (1954 plan to use US airpower to relieve Dien Bien Phu)
1981 plan to use Delta to rescue 500 US POWs in Laos (compromised by Bo Gritz)
HONEY BADGER (2nd Delta rescue plan for Iranian embassy hostages, using rocket-assisted MC130s)
1985 plan to use Delta and ST6 to rescue Western hostages in Beirut after TWA847 hijacking
PACIFIC WIND (1990 SOCOM plan to liberate Western hostages held by Saddam before DESERT SHIELD- thankfully, not needing to be used)
1996-97 IFOR/SFOR plans to use SAS, Delta, ST6 and other NATO specops to arrest Radovan Karadzic and Ratko Mladic in Bosnian Serb entity