Nasidytes is an extinct genus of loon (Gaviiformes) that lived during the early Eocene in what is now Great Britain.

[1] The holotype of Nasidytes ypresianus, NMS.Z.2021.40.24, was collected in 1992 by Michael Daniels, in Walton-on-the-Naze, Essex, UK.

The holotype is a partial skeleton including the mandible and most major wing, pectoral girdle, and leg bones.

The generic name is derived from the Latin nasus ("nose", in reference to the semantically related word "Naze" in the name of the type locality) and the Greek δύτες (dytes), meaning "diver".

The single preserved thoracic vertebra exhibits hollow spaces called pleurocoels, which are present in many neornithine stem group representatives but not in modern loons.