Karl Kaspar von der Leyen (18 December 1618 – 1 June 1676) was Archbishop-Elector of Trier and a Prince-Elector of the Holy Roman Empire from 1652 to 1676.

The consequences of the recently ended Thirty Years' War presented the new archbishop with many hard tasks, for example, the population of the archiepiscopal state had declined to approximately 300,000 people.

His policy towards the Allies had destroyed many buildings; so he had to restore the country's infrastructure, especially the justice and agriculture systems, to promote development.

He founded an orphanage for boys in Trier and endowed scholarships for the training of nobles' sons to become priests, and in 1668, he had the Kurtrierische Landrecht ("Electoral-Trier Common Law") published.

In 1654 he made his younger brother Damian Hartard von der Leyen the Archbishop of Mainz and Provost and Archdeacon of Karden, titles under the Archbishopric of Trier.