Muriel E. Mussells Seyfert (born Muriel Elizabeth Mussells, February 3, 1909 – November 9, 1997) was an American astronomer best known for discovering a "ring nebulae" (planetary nebulae) in the Milky Way while working at the Harvard College Observatory in 1936 as a human computer.

Muriel was born on February 3, 1909, in Danvers, Massachusetts, the daughter of George and Stella Mussells.

[1] Mussells Seyfert was employed as a human computer at the Harvard College Observatory.

By examining photographic plates taken at Harvard’s astronomical station at Bloemfontain, South Africa, she discovered three new ring nebulae in the Milky Way galaxy in the mid-1930s.

[2][5] Muriel's sister, Sylvia Mussells Lindsay, also worked as a Harvard computer and discovered the first dwarf galaxy, the Sculptor system.