  We explore the potential of Pulsar Timing Arrays (PTAs) such as NANOGrav,
EPTA, and PPTA to detect the Stochastic Gravitational Wave Background (SGWB) in
theories of massive gravity. In General Relativity, the function describing the
dependence of the correlation between the arrival times of signals from two
pulsars on the angle between them is known as the Hellings-Downs curve. We
compute the analogous overlap reduction function for massive gravity, including
the additional polarization states and the correction due to the mass of the
graviton, and compare the result with the Hellings-Downs curve. The primary
result is a complete analytical form for the analog Hellings-Downs curve,
providing a starting point for future numerical studies aimed at a detailed
comparison between PTA data and the predictions of massive gravity. We study
both the massless limit and the stationary limit as checks on our calculation,
and discuss how our formalism also allows us to study the impact of massive
spin-2 dark matter candidates on data from PTAs.
