Öxarárfoss (Icelandic pronunciation: [ˈœksarˌaurˌfɔsː] ) is a waterfall in Þingvellir National Park, Iceland. It flows from the river Öxará over the Almannagjá [ˈalˌmanːaˌcauː]. The pool at the base of the waterfall is filled with rocks and is often extremely icy during winter.

The waterfall is one of the main attractions of Þingvellir National Park and there is a path from the nearby car park leading up to it.