Vásárosnaményi Báró Eötvös Loránd, better known as Loránd Eötvös or Roland Eotvos (July 27, 1848 - April 8, 1919) was a Hungarian physicist.
Eötvös is remembered today for his experimental work on gravity, in particular his study of the equivalence of gravitational and inertial mass (the so-called weak equivalence principle) and his study of the gravitational gradient on the Earth's surface.
The weak equivalence principle plays a prominent role in relativity theory and the Eötvös experiment was cited by Albert Einstein in his 1916 paper The Foundation of the General Theory of Relativity.
Measurements of the gravitational gradient are important in applied geophysics, such as the location of petroleum deposits. The CGS unit for gravitational gradient is named the eotvos in his honor.
From 1886 until his death, Roland Eötvös researched and taught in the University of Budapest, which in 1950 was named after him (Eötvös Loránd University).