Morley Cigarettes are a fictional brand of smokes which show up all over American television and films (and, as synecdouche tells me, video games). They are possibly one of the most famous 'fake brands' used in American TV shows, probably because The X-Files character The Cigarette Smoking Man was always smoking them, meaning they and their packaging got a great deal of screen time.
Their origin is somewhat clouded. There was an episode of The Dick Van Dyke Show from 1961 which showed a box of chocolate cigarettes with the name 'Morley' on them. The first actual cigarette with the Morley brand seems to be one from a 1963 episode of Twilight Zone ("Nightmare at 20,000 feet") in which a young William Shatner pulls out a Morley and makes as if to light it on an airplane before being shown a 'NO SMOKING' sign.
Since then, they've shown up everywhere. The most familiar version of them is a cigarette box which closely mimics the packaging of actual Marlboro cigarettes. There are differences - the coat of arms, the health warning, and of course the name - but the design is generally similar enough that Marlboro is probably not unhappy with the result. Wikipedia has a list of known appearances if you're curious.
Why did Morleys become so widely available in the alternate world of American TV and film? Probably some of this has to do with the Public Health Cigarette Smoking Act passed by the U.S. Congress in 1970. In addition to mandating the now-familiar U.S. Surgeon General's warning on cigarette packaging, this act banned the advertising of tobacco products on television and radio. In addition to preventing straight interstitial ads for cigarettes, this act likely meant that the display of actual cigarette brands on television would run afoul of the law. TV prop masters needed a brand name and packaging which strongly evoked 'cigarette' without crossing this line. Unlike beer cans or bottles, for example, cigarette boxes are not always obviously cigarettes from their form alone. They are a nondescript size and shape (about that of a deck of playing cards, for example) and are small enough that if they're lying around on a set, it might be difficult to determine what they are. Morley's branding, so close to the heavily-advertised Marlboro livery, would immediately make it clear to viewers that they are looking at cigarettes.
This is what you get for not doing a *careful* search before writing. My searches for 'Morley Cigarettes' didn't show me this node, so I apologize for redundant information.