The examination of a collection of nudibranchs (Mollusca: Gastropoda: Heterobranchia) obtained during several expeditions to international waters off Newfoundland, North Atlantic, revealed the presence of rare species, new records for the area, and an undescribed species of Tritonia (described herein). This includes the first record of Dendronotus niveus Ekimova, Korshunova, Schepetov, Neretina, Sanamyan and Martynov, 2015 from the Atlantic Ocean and numerous specimens of the rare species Doridoxa ingolfiana Bergh, 1899, which is here redescribed. Other species collected are Flabellina cf. salmonacea (Couthouy, 1838), Dendronotus frondosus (Ascanius, 1774), Dendronotus robustus A. E. Verrill, 1870, Aldisa zetlandica (Alder & Hancock, 1854), Onchidoris bilamellata (Linnaeus, 1767), Colga villosa (Odhner, 1907) as well as an unidentified species of Aeolidiella. Anatomical characteristics and genetic barcode data are used to identify the species whenever it was possible. Ecological data, including substrate, associated fauna and bathymetric range are provided.