Parazoanthus swiftii is a zoantharian (family Parazoanthidae) found in shallow Caribbean and Gulf of Mexico reef environments, forming epizoic colonies on gorgonian corals and sponges. The species was one of the earliest zoantharians studied for its secondary metabolite chemistry, and several bioactive compounds with cytotoxic and anti-inflammatory properties have been isolated from it. It is a common epizoic organism on Caribbean gorgonians and represents an important component of reef epibenthic communities. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.