Formerly Norway's greatest acrobatic dwarf, Dietrich was hired to spy on Eriksson's work by posing as a gargoyle on his house.

Jade is a mercenary for hire, entrepreneur, ally of the Quest team, and an old flame of Race Bannon. In "Double Danger", she exposes Korchuk, an agent of Dr. Zin who is pretending to be Race, after kissing him. When Jonny asks how Jade knew Korchuk was an imposter, she simply replies, "There are some ways a woman cannot be fooled!"

Dr. Phorbus was a scientist who sought to create the ultimate super soldier by breeding a race of humanoid reptilian warriors. His ultimate creation was the Reptilian, a cross between a human and a dinosaur, who obeyed Phorbus' commands.

The Adventures of Jonny Quest ran for only one season of twenty-six episodes, but those episodes were so popular that they continued for many years in reruns. Decades later, new episodes were produced for syndication, as well as several made-for-television movies, a comic book series, and a more modern revival series called The Real Adventures of Jonny Quest.