August Ferdinand Möbius (November 17, 1790 – September 26, 1868) (pronounced ) was a German mathematician and theoretical astronomer. He was born in Schulpforta, Saxony-Anhalt, Germany and died in Leipzig.

He is best known for his discovery of the Möbius strip, a non-orientable two-dimensional surface with only one side when embedded in three-dimensional Euclidean space. It was independently discovered by Johann Benedict Listing around the same time. The Möbius configuration, formed by two mutually inscribed tetrahedra, is also named after him. Möbius was the first to introduce homogeneous coordinates into projective geometry. Möbius transformations, important in projective geometry, are not to be confused with the Möbius transform of number theory, which also bears his name. His interest was also in number theory, and the important Möbius function μ(n) and the Möbius inversion formula are named after him. In Euclidean geometry, he systematically developed the use of signed angles and line segments as a way of simplifying and unifying results.

Möbius studied under Carl Friedrich Gauss and Johann Pfaff.