John I (; 24 August 1358 – 9 October 1390) was King of Castile and León from 1379 until 1390. He was the son of Henry II and of his wife Juana Manuel of Castile.
- Occupation
- warrior, politician
- Position held
- Lord of Biscay, king, Monarch of Castile and Leon
- Citizenship
- Crown of Castile
- Born
- August 24, 1358
- Died
- October 9, 1390
