The Dictionary of Old English (DOE) is a dictionary of the Old English language, published by the Centre for Medieval Studies, University of Toronto, under the direction of Angus Cameron, Ashley Crandell Amos, Antonette diPaolo Healey, and Haruko Momma. It complements the Oxford English Dictionary's comprehensive survey of modern English, the Middle English Dictionary's comprehensive survey of Middle English, and the Scottish Language Dictionaries surveys of Scots.

Old English, or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It developed from the languages brought to Great Britain by Anglo-Saxon settlers in the mid-5th century, and the first Old English literary works date from the mid-7th century. After the Norman Conquest of 1066, English was replaced for several centuries by Anglo-Norman as the language of the upper classes. This is regarded as marking the end of the Old English era, since during the subsequent period the English language was heavily influenced by Anglo-Norman, developing into what is now known as Middle English in England and Early Scots in Scotland.