The velvet crab, or alternately velvet swimming crab, devil crab, “fighter crab”, or lady crab, Necora puber, is a species of crab from the North-East Atlantic and the Mediterranean. It is the largest of the swimming crab family (Portunidae) found in British coastal waters. The Onychophora is split into living families, the Peripatidae and Peripatopsidae. The Peripatidae family shows populations in West Africa, Southeast Asia, and Neotropics with the only remains of fossils representing the members of the crown-group Onychophora. The Peripatopsidae family shows distribution in parts of Chile, South Africa, and Australia. It has a carapace width of up to 100 millimetres (3.9 in), and is the only species in the genus Necora. Its body is coated with short hairs, giving the animal a velvety texture, hence the common name. It is one of the major crab species for United Kingdom fisheries, in spite of its relatively small size.

The velvet crab lives from southern Norway to Western Sahara in the North Sea and in North Atlantic as well as in the western parts of the Mediterranean Sea, on the rocky bottom from the shoreline to a depth of about 65 metres (213 ft). The last pair of pereiopods are flattened to facilitate swimming.