Clan Bissett (Bisey, Byset, Bisset or Bissert) is a Scottish clan. The clan is recognized by the Lord Lyon King of Arms but does not have a clan chief recognized by the Lord Lyon King of Arms. The surname Bissett is also considered a sept of the Clan Fraser of Lovat.
The surname Bisset is believed to be of Norman origin and was brought to Scotland when William the Lion returned from captivity in England, accompanied by the Biseys. The Bysets settled in Nottinghamshire and Derbyshire in England. They appear with other Norman families to have successfully established themselves and gained land in Morayshire, Scotland. The power of the family spread and persons bearing the surname witnessed several charters in the 13th and 14th centuries.
 
The rising fortunes of the family were eclipsed however by a feud with the Earl of Atholl. In 1242 at a tournament held at Haddington, Walter Byset, Lord of Aboyne was defeated by the youthful Earl of Atholl. Allegedly, Byset, in a fit of anger murdered the earl while he slept and then set fire to his house to conceal the crime. Walter Byset and his nephew John then fled to Ireland and then to England. The feud followed the two fugitives as a pardon was later granted to the son of the Earl of Atholl for killing some Bysets in Ireland.
 
The principal line of the clan is now that of Bisset of Lessendrum, one of the oldest families in Aberdeenshire. Lessendrum was the ancestral home to the Bisset of Lessendrum family who were granted the estate in 1252. The Bisset's built a fortified house shortly afterwards, which was remodeled in 1470 (L plan), in 1816 and in 1836. The 1836 remodel was undertaken by Architect Archibald Simpson. The house was destroyed by fire in 1928, due to a failure in the heating system in the furnace room. The remains are now overgrown with ivy.