Macclennan is a Scottish surname of Gaelic origin, derived from the Gaelic word mac an t-seallamh, meaning son of the sea man. It is believed to have originated in the 13th century, and the name is associated with the Macclennan clan, which was a powerful and influential family in Scotland. The name is thought to have been brought to Scotland by the Normans, who introduced their own surnames and naming conventions. Over time, the name Macclennan has evolved into various forms, including Macclennan, Macclennan, and Macclennan. Today, the name is still found in Scotland and is also used in other countries, including Canada and Australia.