Batman Arkham: Court Of Owls - 10 Characters That MUST Appear
4. Dr. Zodiac
While Dr. Zodiac doesn't feature in any major comics, he has this one major benefit; his powers would let him be the coolest boss battle imaginable.
In World's Finest Comics 268, the magician manages to acquire magical coins inscribed with the various zodiac. The coins bestow the doctor various powers based on the sign - for example, the Leo coin lets Zodiac change his head into that of a lion.
The idea of this becoming a fight mechanic is more or less golden. Having the different coins translate into different attacks and scenarios would make for an interesting dynamic for a boss fight, as well as a clever way to use a character who hasn't seen use since the eighties.