The paper revisits the taxonomy of eastern North Pacific killer whales (Orcinus orca), specifically focusing on the 'resident' and 'Bigg’s' (or 'transient') ecotypes. The authors review ecological, morphological, and genetic data to determine whether these ecotypes should be recognized as separate species. They conclude that both ecotypes warrant species status, with Bigg’s killer whales classified as *Orcinus rectipinnus* and resident killer whales as *Orcinus ater*. The review highlights distinct genetic, morphological, and behavioral differences between the two ecotypes, including dietary specialization, social structure, and acoustic characteristics. The findings support the proposal for species-level classification, emphasizing the need for conservation efforts tailored to each ecotype. The paper also discusses the historical context of taxonomic revisions and the implications for conservation management.The paper revisits the taxonomy of eastern North Pacific killer whales (Orcinus orca), specifically focusing on the 'resident' and 'Bigg’s' (or 'transient') ecotypes. The authors review ecological, morphological, and genetic data to determine whether these ecotypes should be recognized as separate species. They conclude that both ecotypes warrant species status, with Bigg’s killer whales classified as *Orcinus rectipinnus* and resident killer whales as *Orcinus ater*. The review highlights distinct genetic, morphological, and behavioral differences between the two ecotypes, including dietary specialization, social structure, and acoustic characteristics. The findings support the proposal for species-level classification, emphasizing the need for conservation efforts tailored to each ecotype. The paper also discusses the historical context of taxonomic revisions and the implications for conservation management.