Queen of Eternia, wife of King Randor. Originally an Earth astronaut named Marlena Glenn who crashed on Eternia. Mother of Adam (He-Man) and Adora (She-Ra).
Queen Marlena Glenn was originally an Earth astronaut who crashed on Eternia and married King Randor. This makes Adam (He-Man) and Adora (She-Ra) half-Earthlings and gives Marlena a unique perspective on Eternian affairs. The Filmation episode “Visitors from Earth” (S1E64) is the canonical source of her origin.
She is strongly implied across the Filmation run to have worked out that Adam is He-Man (most famously in The Rainbow Warrior, S2E3), though she never confirms this. The 2002 MYP continuity and the Revelation continuation both preserve and develop the implied knowledge.
Catalogue source: heman.fandom.com (CC BY-SA 3.0).