Black Holes are regions of space-time where the gravitational field is so strong that not even light can escape. There has been much written on black holes, however in most cases they are treated as isolated objects. The author has found a number of cases in which the interaction of a black hole with another strong-field system (such as the background universe or another black hole) could be treated analytically. This includes using the powerful method of matched asymptotic expansions. In this book the author considers these wider ranging problems and examples for the first time. This book will be widely read by all those working in gravitation, and PhD students in mathematical physics.