John Christopher Baillie Papaloizou FRS (born 1947) is a British theoretical physicist.

Papaloizou is a professor at the Department of Applied Mathematics and Theoretical Physics (DAMTP) at the University of Cambridge.

He works on the theory of accretion disks, with particular application to the formation of planets.

The title of his thesis is The Vibrational Instability in Massive Stars.

[1] Papaloizou also made major contributions in various areas such as the radial-orbit instability, toroidal modes in stars and different instabilities in accretion disks.