  We present calculations for the anticipated shadow sizes of Sgr A* and the
supermassive black hole in the galaxy M87 in the context of the MOG modified
theory of gravity (also known as Scalar-Tensor-Vector-Gravity, or STVG). We
demonstrate that mass estimates derived from stellar and gas dynamics in the
vicinity of these black holes are the Newtonian masses of the black holes even
in the MOG theory. Consequently, shadow sizes increase as a function of the key
dimensionless MOG parameter alpha that characterizes the variable gravitational
coupling coefficient G, and may offer an observational means to distinguish the
MOG theory from standard general relativity.
