Hagan Mountain is a multi-peak mountain located in the North Cascades, in Whatcom County of Washington state. It is situated north of Marblemount, within North Cascades National Park. Its nearest higher peak is Mount Blum, to the north, with Bacon Peak to the south. Precipitation runoff and glacier meltwater from the large Hagan Glacier and smaller Hidden Creek Glacier on the mountain drains into tributaries of the Skagit River.