Wohlfahrtiimonas chitiniclastica is a rare cause of fatal septicemia in humans, and recently reported in a white-tailed deer (Odocoileus virginianus). We describe fatal septicemia associated with W. chitiniclastica in a short-beaked common dolphin (Delphinus delphis) with fibrinosuppurative and necrotizing pulmonic, aortic, and mitral valve endocarditis.