  No-hair theorems exclude the existence of nontrivial scalar and massive
vector hair outside four-dimensional, static, asymptotically flat black-hole
spacetimes. We show, by explicitly building nonlinear solutions, that black
holes can support massive graviton hair in theories of massive gravity. These
hairy solutions are, most likely, the generic end state of the recently
discovered monopole instability of Schwarzschild black holes in massive
graviton theories.
