Oceanobdella khani n. sp. is described from the plain sculpin, Myoxocephalus jaok, from Bristol Bay, Alaska, in the eastern Bering Sea. Prevalence was never greater than 10% in any single collection; maximum intensity was 12 leeches per host, but most fish had 5 or fewer leeches. Oceanobdella khani possesses generic characters of small oral sucker, 5 pairs of testisacs, unremarkable terminal male reproductive organs, coelomic system lacking pulsatile vesicles, and 3 pairs of eyes on the oral sucker–trachelosome. Oceanobdella khani is distinguished from other species in the genus by solid black pigmentation on the urosome, clitellum, trachelosome, and most of the oral sucker except for an unpigmented margin. The pigmentation of the caudal sucker is highly variable, ranging from overall mottled blackish gray to completely unpigmented. The caudal sucker lacks ocelli. Intestinal ceca are large, crop ceca are directed anteriorly, and postceca are separate for their entire length.