Earl () is a rank of the nobility in the United Kingdom. The title originates in the Old English word eorl, meaning "a man of noble birth or rank". The word is cognate with the Scandinavian form jarl, and meant "chieftain", particularly a chieftain set to rule a territory in a king's stead. After the Norman Conquest, it became the equivalent of the continental count (in England in the earlier period, it was more akin to a duke; in Scotland, it assimilated the concept of mormaer). Alternative names for the rank equivalent to "earl" or "count" in the nobility structure are used in other countries, such as the hakushaku (伯爵) of the post-restoration Japanese Imperial era.

In modern Britain, an earl is a member of the peerage, ranking below a marquess and above a viscount. A feminine form of earl never developed; instead, countess is used.