Alastor may refer to a number of people and concepts in Greek mythology.

It may also refer to:

Fictional

Alastor Cluster, a fictional setting in three of American writer Jack Vance's novels Alastor Moody, a fictional character in the Harry Potter universe Alastor the Radio Demon, a fictional character in the adult animated series, Hazbin Hotel

Others Alastor, or The Spirit of Solitude, a 1815 poem by Percy Bysshe Shelley Alastor (wasp), a genus of wasp Alastor: Book of Angels Volume 21, a 2014 album by violist and multi-instrumentalist Eyvind Kang

See also Alistair, Scottish name