Thanks to Superhero Movie News we’ve got this leaked post credits scene to X-Men: Days of Future Past!
Sure looks like En Sabah Nur aka Apocalyse to me. Well a young version of him. The people also seem to be chanting En Sabah Nur. In the last pic the 4 figures in the distance might be his 4 horsemen.
X-Men: Apocalypse is set for release on May 27th, 2016.