In the 1982 film, The Verdict, Seneca plays the supporting role of Dr. Thompson, a small-town women's hospital physician brought in by attorney Frank Galvin (Paul Newman) to support his belief that two famous doctors' incompetence left his client alive but in a coma. Seneca's performance, while subdued, brings a gritty realism to the court proceedings and was one of his more important film roles. Arguably his most well-known roles are that of bluesman Willie Brown in Crossroads (1986) and Dr. Meddows in The Blob (1988), the evil head of a government team sent to contain the title creature.