Usually from Gibson itself but, of course, all borrowed types and sometimes absolutely equivalent copies apply here as well.
Characteristics: Humbuckers and a fat and heavy body which tends to make it sound fatter without lacking a decent amount of treble and bite. The construction of the guitar is responsible for the sound which usually means a mahogany body with a sized maple top that’s about one inch thick at the highest point. The bridge pickup provides the classic rock sound, while it gets bluesy round the neck (less gain on your amp, please). A headstrong hollow tone means the intermediate position is suitable for both clean and distorted sounds. By the way, the less husky PAF pickups (which are available under miscellaneous names by almost any brand) still suit a Les Paul best, although Gibson has started building in louder gauges recently as well.

Sometimes people accuse the Les Paul of not being as versatile as other guitars but with its three pickup positions together with the separate tone and volume controls for each pickup (a simple preset option if you like – a real blessing, especially playing live) it is capable of producing quite a few different sounds. The alleged limits concerning its possibilities are, in the end, in the ear of the beholder.

Besides, the classic rock sound (or at least one important type of rock) is made by using a Les Paul and a tube amp stack at full blast.