Alejandro Jenkins (born 17 October 1979, San José, Costa Rica) is a Costa Rican theoretical physicist.
He is currently a professor at the University of Costa Rica and a member of Costa Rica's National Academy of Sciences.
Previously, he was a researcher at the California Institute of Technology (Caltech), the Massachusetts Institute of Technology (MIT), and Florida State University (FSU).
He has worked on applications of quantum field theory to particle physics and cosmology, as well as on self-oscillating dynamical systems and quantum thermodynamics.