Light beer is a beer, usually a pale lager, that is reduced in alcohol content or in calories compared to regular beers. Light beers may be chosen by beer drinkers who wish to manage their alcohol consumption or their calorie intake; however, they are sometimes criticised for being less flavourful than full-strength beers, or for tasting or actually being watered down.

After some scattered fits and starts, light beer began to be mass marketed, and accepted by consumers, in the early to mid-1970s, following two years of test marketing and promotion, then a nationwide rollout of Miller Lite in 1975 (then known merely as "Lite Beer from Miller").

There is widespread confusion between reduced calorie/reduced alcohol "light beer" and the historic term "light lager", which distinguished pale or golden lagers with lighter body from the traditional amber lagers and other inherently darker beers.