This Collective Article presents new information about the occurrence of 21 taxa that belong to six Phyla: one Cnidaria, one Ctenophora, two Annelida, four Mollusca, two Arthropoda, and eleven Chordata. These records were reported from ten countries from the western to the eastern Mediterranean Sea as follows: Spain: early colonization signs of the Mar Menor lagoon by the cigar jellyfish Olindias muelleri; France: second record of the sea chub of the genus Kyphosus in French Mediterranean waters; Italy: first record of the marbled crab Pachygrapsus maurus in Sardinian waters; first records of the polychaetes Malmgrenia polypapillata and Levinsenia tribranchiata in the Tyrrhenian Sea; new record of the deep-sea squid Ancistrocheirus lesueurii in the Tyrrhenian Sea; first record of the pignosed arrowtooth eel Dysomma brevirostre in the Adriatic Sea; Tunisia: first documented record of the blue butterfish Stromateus fiatola and new record of the iconic great white shark Carcharodon carcharias in the Gulf of Gabes; Slovenia: first records of the sea slug Diaphorodoris alba and the sharpnose sevengill shark Heptranchias perlo; Montenegro: new record of the rare tope shark Galeorhinus galeus; Greece: new records of the rabbitfish Chimaera monstrosa and the electric ray Tetronarce nobiliana; first published record of the nuribranch Discodoris rosi; first record of the goblin shark Mitsukurina owstoni, unreported so far from the entire Mediterranean; Turkey: first record of the ctenophore Hormiphora plumosa at country level; first records of the anomuran decapod Munida speciosa and the Mediterranean tripodfish, Bathypterois mediterraneus from the Levantine Sea; Cyprus: first documented record of the nuribranch Scyllaea pelagica; Lebanon: first record of the killer whale Orcinus orca from the Levantine Sea.