The Komondor (/ˈkɒməndɔːr, ˈkoʊm-/), also known as the Hungarian sheepdog, is a large, white-coloured Hungarian breed of livestock guardian dog with a long, corded coat.

Sometimes referred to as 'mop dogs' due to their appearance, the Komondors are a long-established dog breed commonly employed to guard livestock and other property. The Komondor was brought to Europe by the Cumans and the oldest known mention of it is in a Hungarian codex from 1544. The Komondor breed has been declared one of Hungary’s national treasures, to be preserved and protected from modification.

Komondors were brought to Hungary by Cumans, the Turkic speaking, nomadic people who settled in Hungary during the 12th and 13th century. The name Komondor derives from *Koman-dor, meaning "Cuman dog". The breed descends from Tibetan dogs and came from Asia with the Cumans, whose homeland might have been near the Yellow River. In the late 10th century, Mongols began to expand their territories at the expense of the Cumans, forcing them to move westwards. Fleeing from the Mongols, they reached the borders of Hungary in the 12th century. Cumans were granted asylum and settled in Hungary in 1239 under Köten Khan. Komondor remains have been found in Cuman gravesites.

The name "quman-dur" means "belonging to the Cumans" or "the dog of the Cumans", thus distinguishing it from a similar Hungarian sheepdog breed which later merged with the Komondor. The name Komondor is found for the first time written in 1544 in the History of King Astiagis by Péter Kákonyi, in Early Modern Hungarian. Later, in 1673, John Amos Comenius mentions the Komondor in one of his works. Today, the Komondor is a fairly common breed in Hungary, its country of origin. Many Komondors were killed during World War II and local stories say that this was because when the Germans (and then the Russians) invaded, they had to kill the dog before they could capture a farm or house that it guarded.

The Komondor is related to the South Russian Ovcharka, the Puli and, by extension, the Pumi, the Mudi, the Polish Lowland Sheepdog, the Schapendoes, the Bearded collie, and the Old English sheepdog. In 1947, the Komondor was used to acquire fresh blood in the rare South Russian Ovcharka. In the 1970s, another Komondor cross was made. It is also believed to be related to the Briard, the Catalonian Sheepdog, the Cão da Serra de Aires, the Pyrenean Shepherd and the Bergamasco shepherd, but the Bergamasco has flocks unlike the Komondor.

The two Hungarian breeds of livestock guardian dogs have evolved independently. This is because the Komondor was developed by a group of people who called it the Kuman-dor, the dog of the Cumans, and the Kuvasz was bred by a different people - the Magyars. For much of Hungary's early history, these two peoples lived in separate areas in Hungary, spoke different languages and so did not mix. As a result, their dogs have little, if any at all, admixture.

The Komondor is a large breed of dog—many are over 30 inches (76 cm) tall. The body is covered with a heavy, matted, corded coat. They have robust bodies, strongly muscled with long legs and a short back. The tail is carried with a slight curl. The body when seen sideways, forms a prone rectangle. The length of body is slightly longer than the height at withers. The Komondor has a broad head with the muzzle slightly shorter than half of the length of the head with an even and complete scissor bite. Nose and lips are always black.

The minimum height of female Komondors is 25.5 inches (65 cm) at the withers, with an average height of 27.5 inches (70 cm). The minimum height of male Komondors is 27.5 inches (70 cm) with an average height of 31.5 inches (80 cm). No upper height limit is given. Komondor females on average weigh between 88–110 lb (40–50 kg) and Komondor males weigh on average between 110–132 lb (50–60 kg).