Joker (DC)

How is the Joker used as the image of the Headlined Villains template, but hasn't ever been headlined himself? It feels really obvious for him to have been headlined at some point, but his page doesn't have the headlined template. I just thought this was strange.

Idk when did Joker (DC) was a nominee. I'm planning to nominate and vote for him as the headlined villain, and I might getting a rule violation.

How would you develop him as the Joker and make him Batman's arch nemesis?

What is the most evil deed the Joker has done?

Thoughts about these two lovers

Joker and Harley Quinn

I know the title main antagonist in Marvel and DC Comics is shared by their most evil and impactful villains (Thanos, Red Skull, Doctor Doom, Galactus)/(Darkseid, Lex Luthor, Joker, Sinestro), but is there any way to determine character(s) who could be "Secondary Antagonists" of the verses? Or are they just too expansive to do so?