Johannes is the eldest and the leader of the Shadow Angels.
Johannes' face is never revealed in the series. His body is draped in dark purple robes and chains and wears what appears to be a helmet-like mask of metal with a cross shaped visor on its face. Johannes appears to be missing the bottom half of his body for some unknown reason but he is constantly suspended from the ceiling in the main altar of Atlandia by the chains covering his body. The interior of his robes appear to have a red lining on the inside and seems that beneath his robes there are even more chains. However, these chains seems to be fashioned in a manor similar to that of chain-mail armor which further adds to the "knight" like appearance Johannes portrays. Unlike the other members of his species, Johannes does not actually seem to have traditional angel-like wings, instead his wings resemble that of bat and for some reason are also draped in his robes.
In the Anime
Apparently, Johannes is a very old Shadow Angel and has the respect and leadership over all the other Shadow Angels, meaning that even Toma (albeit usually reluctantly) has to follow his orders. By the end of the first anime series of Aquarion, he along with the few remaining Shadow Angels, (Lensi, Golshi, Silver, and Shila) give up their bodies to the Tree of Life to be reincarnated. Their subsequent fates are unknown but with he Tree of Life dead, it can be assumed that like the rest of their kind, they instead died as the tree withered away.