Jayna and Zan, Night and Fog. Two pairs of twin siblings with shape shifting powers used for good and evil, aiding and ailing heroes.
The Wonder Twins came from an alien world of Exxor-One, Night and Fog from Nazi Germany of Earth-Two. Zan able to transform into any liquid form and Night into any animal. Fog can transform into a gaseous state while Night emits total darkness consuming anyone present.
While Zan and Jayna aided the Super Friends who tutored them in superheroics, Fog and Night were foes of the All-Star Squadron.