Frederick van Sierck (died 20 July 1322) served as Bishop of Utrecht from 1317 until his death in 1322.
[1] Frederick van Sierck was the protégé of William III, Count of Holland, who had managed to get him elected to the bishopric of Utrecht.
The construction of the Dom Tower of Utrecht began during Frederick's episcopate.
The theory that the bishop wanted a strong defendable tower where he would be able to retreat in times of danger, is not universally accepted.
Frederick van Sierck was buried in a chapel named after him in the Dom Church.