Triggerfish are about 40 species of often brightly colored marine ray-finned fishes belonging to the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacific. Most are found in relatively shallow, coastal habitats, especially at coral reefs, but a few, such as the oceanic triggerfish (Canthidermis maculata), are pelagic. While several species from this family are popular in the marine aquarium trade, they are often notoriously ill-tempered.

The triggerfish family, Balistidae, was first proposed in 1810 by the French polymath Constantine Samuel Rafinesque. The closest relatives to the triggerfishes are the filefishes belonging to the family Monacanthidae and these two families are sometimes classified together in the suborder Balistoidei, for example in the 5th edition of Fishes of the World. Other authorities, however, also include the families Aracanidae and Ostraciidae within the suborder Balistoidei.

Triggerfish have both a common name and a scientific name that refers to the first spine of the dorsal fin being locked in place by the erection of the shorter second trigger spine, and unlocked by depressing the second spine. In the scientific name of the type genus Balistes this is taken directly from the Italian pesce balestra, the "crossbow fish", ballista originally being a machine for throwing arrows.

The largest member of the family, the stone triggerfish (Pseudobalistes naufragium), reaches 1 m (3.3 ft), but most species have a maximum length between 20 and 50 cm (8–20 in). Triggerfish appear to have grown to even larger sizes in the geologic past, with the extinct fossil species Balistes crassidens and Balistes vegai, both from the Miocene of the Caribbean, potentially reaching up to 1.8 metres (5.9 ft), making them the largest triggerfishes known to have ever existed.

Triggerfish have an oval-shaped, highly compressed body. The head is large, terminating in a small but strong-jawed mouth with teeth adapted for crushing shells. The eyes are small, set far back from the mouth, at the top of the head. The anterior dorsal fin is reduced to a set of three spines. The first spine is stout and by far the longest. All three are normally retracted into a groove. Characteristic of the order Tetraodontiformes, the anal and posterior dorsal fins are capable of undulating from side to side to provide slow movement and comprise their primary mode of propulsion. The sickle-shaped caudal fin is used only to escape predators.

The two pelvic fins are overlaid by skin for most of their length and fused to form a single spine, terminated by very short rays, their only external evidence. Gill plates (opercula), although present, are also not visible, overlaid by the tough skin, covered with rough, rhomboid scales that form a stout armor on their bodies. The only gill opening is a vertical slit, directly above the pectoral fins. This peculiar covering of the gill plates is shared with other members of the Tetradontae. Each jaw contains a row of four teeth on either side, while the upper jaw contains an additional set of six plate-like pharyngeal teeth.

As a protection against predators, triggerfish can erect the first two dorsal spines: the first (anterior) spine is locked in place by erection of the short second spine, and can be unlocked only by depressing the second, "trigger" spine, hence the family name "triggerfish".

With the exception of a few species from the genus Xanthichthys, the sexes of all species in this family are similar in appearance.