Peter of Aspelt (c. 1245 - 5 May 1320) was the Archbishop of Mainz from 1306 until 1320, and the Bishop of Basel from 1297 until 1306.

Peter was born in Luxembourg. He was educated in the Abbey of St Simeon in Trier, and after his study in 1280 became a minister in Riol and Birthingen, and later in Trier. In 1286 he was made the chaplain and physician of King Rudolph I. As Peter was not a nobleman, he did not receive a provostry in Trier, and instead in 1289 entered the service of King Wenceslaus II of Bohemia, serving as his chancellor from 1296 until 1305. Peter arranged the alliance between Wenceslaus and Albert I of Austria, and when Albert was elected king of Germany he was rewarded with the Bishopric of Basel.

On 15 January 1300 Pope Boniface VIII sent him to Mainz with the intention of him succeeding Gerard II of Eppstein. When Gerard died in 1305, the Cathedral chapter still held the right to elect the next archbishop, but it was split between Emich of Schöneck and Emich of Sponheim. Both candidates appealled to Pope Clemens V for confirmation, but he instead chose Peter in 1306. As the House of Luxembourg had also worked to ensure Peter become the next archbishop, he took a pro-Luxembourg policy. This was confirmed when Peter managed to influence the cathedral chapter of Trier to select Baldwin of Luxembourg as the next archbishop.

King Philip IV of France believed that the three Rhenish archbishops were under his influence, and so he put forward his brother Charles III of Valois for election as the next Holy Roman Emperor. However Peter engineered the election of Henry of Luxembourg, who was unanimously voted for by the electors on 27 November 1308. Peter gained the close trust of Henry, and together they enthroned Henry's brother John the Blind as King of Bohemia in 1310. Also in 1310 Peter held an important regional diet concerned with church legislation at the demands of the Pope.

In 1311 Henry went to Italy to deal with the Lombard city-states and receive coronation from the Pope, leaving Peter hin charge of the Empire. However the Italian campaign was a disaster. Henry was defeated by the Lombards who received support from a bitter King Philip IV of France, and he died in Siena in 1313 after a short illness. The empire quickly crumbled into a power-struggle. Peter and Henry II of Virneburg, Archbishop of Cologne, attempted to get John of Bohemia crowned king but failed. Instead in 1314 the double election of Louis IV of Upper Bavaria and Frederick I of Austria occurred, and Germany was for several years embroiled in civil war. Both candidates then asked Pope John XXII for the Imperial crown. Peter died in Mainz in 1320 before the resolving of the dispute, and was buried in Mainz cathedral.

Preceded by:

Peter of Aspelt

Succeeded by:

Gerard II of Eppstein Archbishop of Mainz
1306 - 1320
Matthias of Bucheck
Peter I Reich of Reichenstein Bishop of Basel
1297 - 1306
Eudes de Granson