Hadriacus Mons is an ancient, low-relief volcanic mountain on the planet Mars, located in the southern hemisphere just northeast of the impact basinHellas and southwest of the similar volcano Tyrrhenus Mons. It has a diameter of 450 kilometres (280 mi). The name was approved in 2007. The flanks of Hadriacus Mons have been eroded into gullies; its southern slopes are incised by the outflow channelDao Vallis.
Hadriaca Patera, a term formerly used for the entire edifice, is now only used for the central caldera, which is 66 kilometres (41 mi) in diameter.