Ruth Kellerhals (born 17 July 1957) is a Swiss mathematician at the University of Fribourg, whose field of study is hyperbolic geometry, geometric group theory and polylogarithm identities.
She received her PhD in 1988, from the same university, with a thesis entitled "On the volumes of hyperbolic polytopes in dimensions three and four".
In 1995 she received her habilitation from the University of Bonn, where she worked at the Max Planck Institute for Mathematics since 1989 until 1995.
She does historical research into the works and life of Ludwig Schläfli, a Swiss geometer.
Also she visited numerous research institutes and universities in Helsinki, Berlin and Budapest.