The Invisibles is an episode of "The Herculoids" segments in the Space Stars show. It first aired 3 October 1981 on NBC.
Summary[]
A chunk of magnilite lands in the Lost Lake of Quasar. Before long, the Herculoids go up against enemies that they cannot see. Zandor soon learns from the Zelos King Zel that his son Eezo and his followers might be the culprits, a theory proven correct when Space Ghost arrives to return the magnilite to space.