Geoffrey William Marcy is an American astronomer. He was an early influence in the field of exoplanet detection, discovery, and characterization. Marcy was a professor of astronomy at the University of California, Berkeley, and an adjunct professor of physics and astronomy at San Francisco State University. Marcy and his research teams discovered many extrasolar planets, including 70 out of the first 100 known exoplanets and also the first planetary system around a Sun-like star, Upsilon Andromedae. Marcy was a co-investigator on the NASA Kepler mission. His collaborators have included R. Paul Butler, Debra Fischer and Steven S. Vogt, Jason Wright, Andrew Howard, Katie Peek, John Johnson, Erik Petigura, Lauren Weiss, Lea Hirsch and the Kepler Science Team. Following an investigation for sexual harassment in 2015, Marcy resigned his position at the University of California, Berkeley.

Upsilon Andromedae is a binary star located 44 light-years from Earth in the constellation of Andromeda. The system consists of an F-type main-sequence star and a smaller red dwarf.