Military laser systems are significantly different from commercial ones. The Department of Defense (DoD) has supported a large laser research-and-development budget, which has resulted in a rich diversity of military laser systems, ranging from the latest nonlinear technology to eye-safe, low-cost, laser-ranging binoculars. This paper reviews the military interests that created the diversity of laser systems, describes some of the more significant developments, and discusses some of the military lasers that can be expected in the future. Military interest in laser systems has been concentrated in four general areas: laser rangefinders and target designators, directed-energy weapons, laser radar, and laser communications. Although the nature of this interest is different from that in the commercial world, DoD funding has enabled significant laser systems to be advanced from laboratory curiosities to reliable and relatively inexpensive commercial successes.