Magog. Human-sized predators covered in a loose, shaggy pelt. They feed on sapient beings which they paralyse with toxin, and reproduce by laying their eggs in another living being: the larvae hatch and consume their host. The most significant Magog character in the series is Rev Bem, who eschews the "brutish violence" of the rest of the Magog. Their leader, or god, is the Spirit of the Abyss: the Magog say that he is their creator. Rev Bem says that the Divine created the Magog: "...the Divine also has nightmares, for he created us." 
Paradine. The Paradines are both referred to as evolved Vedrans, as well as the first race of sentient beings in the galaxy. Trance Gemini hypothesizes that the Paradines may have had a "hand in its [the universe's] creation". These problems are not expanded upon or resolved during the show's run.
Than-Thre-Kull. A sentient species: the Than are humanoid, in the sense that they have two arms ending in hands, and two legs; they are insectoid, in that their bodies are covered in a hard carapace, they have compound eyes and ant-like mandibles. Than are slightly smaller than humans on average, standing approximately 1.5 metres tall.