He is first mentioned in The Master Mind of Mars, when Valla Dia tells her story to Vad Varo. It turns out that after Valla Dia rejected him, Jal Had attacked Duhor and easily took over the royal palace. He took all the women hostage.Valla Dia only escaped by disguising herself. It is asumed that Jal Had eventually left Duhor again since Valla Dia and Vad Varo return there at the end of the story.
Jal Had is actually seen in person in Synthetic Men of Mars. Here it is revealed he has the unpleasant habit of including intelligent lifeforms in his famous zoo. He captures both Vor Daj (who at the time was posing as the hormad Tor-Dur-Bar) and Janai, putting the former in his zoo and attempting to make te later his wife. Vor Daj escapes from the zoo however and also sets free the other creatures imprisoned there, causing massive mayhem. Jal Had meets his end when he is killed by Bal Tab. Considering his reputation, his death is unlikely to be deeply regretted by anybody.