Eleanor of Viseu was a Portuguese infanta (princess) and later queen consort of Portugal. She is considered one of her country's most notable queens consort and one of the only two who were not foreigners. To distinguish her from other infantas of the same name, she is commonly known as Eleanor of Viseu or Eleanor of Lancaster. In Portugal, she is known universally as Rainha Dona Leonor.

John II, called the Perfect Prince, was King of Portugal from 1481 until his death in 1495, and also for a brief time in 1477. He is known for re-establishing the power of the Portuguese monarchy, reinvigorating the Portuguese economy, and renewing his country's exploration of Africa and Asia.