Cartimandua or Cartismandua (ruled c. 43 – 69) is a queen of the Brigantes, a Celtic people in what is now Northern England, in the 1st century.

She comes to power around the time of the Roman conquest of Britain, and forms a large tribal agglomeration that becomes loyal to Rome.

She is known exclusively from the work of a single Roman historian, Tacitus, though she appears to have been widely influential in early Roman Britain.

Her name may be a compound of the Common Celtic roots *carti- "chase, expel, send" and *mandu-, "pony".