Eleanor of Viseu (2 May 1458 – 17 November 1525; Portuguese: Leonor de Viseu [liu'no? d? vi'zew]) was a Portuguese infanta (princess) and later queen consort of Portugal.
To distinguish her from other infantas of the same name, she is commonly known as Eleanor of Viseu (after her father's title) or Eleanor of Lancaster (Lancaster, a name used by some Portuguese royals after her great-grandmother Queen Philippa of Lancaster).
In Portugal, she is known universally as Rainha Dona Leonor.
She is considered one of the most notable Portuguese queen consorts.
She was the second of only two queen consorts of Portugal who were not foreigners.