William I of Hesse (German: Wilhelm) (4 July 1466 – 8 February 1515) was the Landgrave of Hesse (Lower Hesse) from 1471 to 1493.

His parents were Louis the Frank (1438–1471) and Mechthild, daughter of Count Louis I of Württemberg.

On 17 February 1488 in Münden, he married Anna of Brunswick-Wolfenbüttel c. 1460 - Worms 16 May 1520], daughter of William IV, Duke of Brunswick-Wolfenbüttel and Elisabeth, Countess of Stolberg, with whom he had five daughters:[1][2] After a pilgrimage to the Holy Land in 1491 where he was dubbed a Knight of the Holy Sepulchre, he probably contracted syphilis.

He abdicated in favor of his brother William II on 3 June 1493, and spent the rest of his life in Spangenberg.

This article about a member of the German nobility is a stub.