Classical Yang-Mills black hole hair in anti-de Sitter space

The properties of hairy black holes in Einstein-Yang-Mills (EYM) theory are reviewed, focusing on spherically symmetric solutions. In particular, in asymptotically anti-de Sitter space (adS) stable black hole hair is known to exist for su(2) EYM. We review recent work in which it is shown that stable hair also exists in su(N) EYM for arbitrary N, so that there is no upper limit on how much stable hair a black hole in adS can possess.