The albacore, Thunnus alalunga, is a type of tuna in the family Scombridae. This species is also called albacore fish, albacore tuna, albicore, longfin, albies, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito (but see bonito), longfin tuna, longfin tunny, or even just tuna. It is the only tuna species which may be marketed as "white meat tuna" in the United States. It is found in the open waters of all tropical and temperate oceans, and the Mediterranean Sea. Lengths range up to 140 cm (4.5 feet) and weights up to 45 kg (99 lb).

Albacore is a prized food, and the albacore fishery is economically significant. Methods of fishing include pole and line, long-line fishing, trolling, and some purse seining. It is also sought after by sport fishers.

The pectoral fins of the albacore are very long, as much as 50% of the total length. The dorsal spines are 8 to 10 in number, and well forward of the rays of the dorsal fin. The anterior spines are much longer, giving a concave outline to the spiny part of the dorsal fin.