Whelks are any of several carnivorous sea snail species with a swirling, tapered shell. Many are eaten by humans, such as the common whelk of the North Atlantic. Most whelks belong to the family Buccinidae and are known as "true whelks." Others, such as the dog whelk, belong to several sea snail families that are not closely related.

True whelks (family Buccinidae) are carnivorous, and feed on annelids, crustaceans, mussels and other molluscs, drilling holes through shells to gain access to the soft tissues. Whelks use chemoreceptors to locate their prey.

Many have historically been used, or are still used, by humans and other animals as food. In a 100-gram (3+1⁄2-ounce) reference serving of whelk, there are 570 kilojoules (137 kilocalories) of food energy, 24 g of protein, 0.34 g of fat, and 8 g of carbohydrates.

Dog whelk, a predatory species, was used in antiquity to make a rich red dye that improves in color as it ages.

The common name "whelk" is also spelled welk or even wilk.

The species, genera and families referred to by this common name vary a great deal from one geographic area to another.

In Japan, whelks (ツブ, 螺, tsubu) are frequently used in sashimi and sushi. In Vietnam, they are served in a dish called Bún ốc - vermicelli with sea snails. Golbaengi-muchim (골뱅이 무침) is a Korean dish consisting of whelks and with chili sauce in a salad with cold noodles. It has been a very popular side dish with alcohol for many generations.

In Australia and New Zealand, species of the genus Cabestana (family Ranellidae) are called predatory whelks, and species of Penion (family Buccinidae) are called siphon whelks.