Enter Steve Englehart and Marshall Rogers ~ and a little story in Detective Comics No. 475 called "The Laughing Fish" in 1978.
Rogers was the artist and Englehart wrote the story: a perfectly goofy crossover from the Silver Age in which the Joker wants a patent on fish that he's poisoned with his trademark Joker-gas induced grins.
It's all very silly except ~ the Joker's back to killing, Comics Code be damned, and he's doing it on a mass scale. By the late 70s, the Comics Code was losing its dictatorial power (though it wouldn't die completely for another 23 years), and this powerhouse creative team took advantage of the new trend in maturing comics to bring back this villain with a vengeance. "The Laughing Fish" segue-ways into the grisly "Sign of the Joker" (Detective Comics No. 476), and the Joker's destiny was sealed: he returned to the DC pantheon more insane and terrifying than ever.
Oh, he would suffer some setbacks along the way (all characters do), but he earned back everything he had lost in the Silver Age and more. And I think it's safe to say he won't be going away again any time soon (even if he is currently MIA in the current DC comics continuity after last year's Death of the Family storyline).
So here he is in all his Marshall Rogers glory, just as I remember him when I was a kid: purple tails and overcoat with matching fedora.
Meanwhile, some notes on the paper doll costume: I got a little overly complicated about this one, but built it in a way that you can ignore my complication if you want.
It's a pet peeve of mine when a paper doll has a long coat, but has no "back" on it. I didn't see any point in drawing two clothing pieces that would be exactly the same save for the coat, so I built the coat to go over the suit.
In the end, probably not the best decision, but I could spend a lot of time rejigging it, or just go with the flow. This won't be the last purple suit set you'll see on here, after all.
There's instructions on the downloadable sheet, and in the end, if you want to print two and glue the second set of pieces together that would work fine too. If you need a guide to color your laughing fish there are plenty of images online.