Totnes (/ˈtɒtnəs/ TOT-nuhss or /tɒtˈnɛs/ tot-NESS) is a market town and civil parish at the head of the estuary of the River Dart in Devon, England. It is about 5 miles (8 km) west of Paignton, about 7 miles (11 km) west-southwest of Torquay and about 20 miles (32 km) east-northeast of Plymouth, adjacent to the South Devon National Landscape. It is the administrative centre of the South Hams District Council. At the 2021 census, the parish had a population of 8,241.

Totnes has a long recorded history, dating back to 907, when its first castle was built. By the twelfth century it was already an important market town, and its former wealth and importance may be seen from the number of merchants' houses built in the sixteenth and seventeenth centuries. Today, the town has a sizeable alternative and New Age community, known as a place where one can live a bohemian lifestyle, though has in recent times also gained a reputation as being a hotspot for conspiracy theorists within the UK.

According to the Historia Regum Britanniae written by Geoffrey of Monmouth in around 1136, "the coast of Totnes" was where Brutus of Troy, the mythical founder of Britain, first came ashore on the island. Set into the pavement of Fore Street is the Brutus Stone, a small granite boulder onto which, according to local legend, Brutus first stepped from his ship. As he did so, he was supposed to have declaimed:

Here I stand and here I rest. And this town shall be called Totnes.

The stone is far above the highest tides and the tradition is not likely to be of great antiquity, being first mentioned in John Prince's Worthies of Devon in 1697. It is possible that the stone was originally the one from which the town crier, or bruiter called out his news; or it may be le Brodestone, a boundary stone mentioned in several 15th century disputes: its last-known position in 1471 was below the East Gate.

The Middle English prose Brut (c. 1419) places the fight between Brutus' general Corineus, and the British giant Gogmagog "at Totttenes", while Cornish antiquary Richard Carew suggested that the fight may have begun near the town, but ended at Plymouth Hoe. The Historia has several other landings at the Totness coast: the Roman general Vespasian, Constantine of Brittany at the port of Totnes, Aurelius Ambrosius and his brother Uther Pendragon attempting to win back the throne of Britain from the usurper Vortigern, the Saxons at war with King Arthur, and in one version Cadwallo fighting against the Mercians. The Historia also mentions the town in a prophecy of Merlin: "after [the dragon of Worcester] shall succeed the boar of Totness, and oppress the people with grievous tyranny. Gloucester shall send forth a lion, and shall disturb him in his cruelty, in several battles. He shall trample him under his feet, and terrify him with open jaws."

The first authentic history of Totnes is in AD 907, when it was fortified by King Edward the Elder as part of the defensive ring of burhs built around Devon, replacing one built a few years earlier at nearby Halwell. The site was chosen because it was on an ancient trackway which forded the river at low tide. Between the reigns of Edgar and William II (959–1100) Totnes intermittently minted coins. Some time between the Norman Conquest in 1066 and the compilation of the Domesday Book in 1086, William the Conqueror granted the burh to Juhel of Totnes, who was probably responsible for the first construction of the castle. Juhel did not retain his lordship for long, however, as he was deprived of his lands in 1088 or 1089, for rebelling against William II.

The name Totnes (first recorded in AD 979) comes from the Old English personal name Totta and ness or headland. Before reclamation and development, the low-lying areas around this hill were largely marsh or tidal wetland, giving the hill much more the appearance of a "ness" than today.