Oubliette Mountain is a 3,070-metre summit in the Canadian Rockies on the Alberta-British Columbia border, rising in the Tonquin Valley between Jasper National Park and Mount Robson Provincial Park as part of The Ramparts. Named by Cyril G. Wates after a hidden dungeon, it shares the dramatic character of nearby Dungeon Peak. The mountain was first climbed in July 1932 by William Hainsworth and Max Strumia with guide Hans Fuhrer, and its East Buttress gained renown after Fred Beckey, Brian Greenwood, and Don Gordon first ascended it in 1962 and Beckey later highlighted the route among his favorite North American climbs. Geologically, it is Cambrian quartzite thrust over younger rock during the Laramide orogeny.