Gaggy

Gaggy, also known as Gagsworth A. Gagsworthy, was once Joker's original sidekick. After their separation, the Joker got a new sidekick, Harley Quinn, and turned Joker from the Clown Prince of Crime, that he knew, to another psychopath.

Batman
In Batman #186, The Joker has gathered a group of criminals and his very own sidekick, a midget clown named Gaggy to commit a series of heists stealing an original or first edition items of antiquated or historical value. As usual the clown prince of crimes thefts bring the attention of Batman and Robin, who after a few bungled attempts at stopping Joker from stealing original models of famous inventions, and an original typewriter, they manage to stop the Joker and his gang from stealing the original Gotham City Hall, and turn the crooks over to the police.

In Batman #682, Gaggy Gagsworthy was once a member of the circus before joining the Joker in a life of crime. As part of the circus, Gaggy was a tightrope walker until the circus hired a new act, The Flying Graysons. Gaggy was then sent to be a clown and part of a freakshow, which he resented. During an act in which Gaggy lashed out on one of his fellow clowns, he caught the attention of the Joker. Willing to kill anyone for laughs, Gaggy teamed up with the Joker, becoming Joker's answer to Robin. Together they committed many crimes using gags and props. They were eventually sent to jail after being defeated by Batman and Robin.

In Batman #686, Gaggy makes a cameo appearance when everybody, including the villains, make their due, when they believe that Batman died.

Gotham City Sirens
In Gotham City Sirens #4, Gaggy is under disguised as The Joker. The Joker not being too happy about the fact that is former girl is out on the town with Bruce Wayne and decides he will do something about it. “Bruce” has a motive for taking Harley around town, and it is not to have an intellectual conversation on the future of Gotham. The Joker shows off some his toys to heal his broken heart by blowing up the one who hurt him and Catwoman and Ivy come to rescue their friend, while “Bruce saves” the day. Catwoman and Ivy then try to convince Harley that “Bruce” is bad and Joker is out to kill her, all Harley takes away from it is that she thinks that the Joker still loves her. He proves that he is not, by blowing her and her friends up in their apartment.

In Gotham City Sirens #5, Harley Quinn takes center stage this issue as the girls deal with the after effects of Hush’s deadly manipulations over the last few months. Basically we saw the Joker crash the Jokermobile through the window at Harley and the sirens. Well they survived this little onslaught and after making Harley see that Mr. J is actually trying to kill her they decide they need to stop him. There are a few more Joker ramblings scenes, but during the fight between the sirens and Joker, we discover that this isn't actually the Joker but his old sidekick, Gaggy.

In Gotham City Sirens #6, hey went to prison together, but Joker ended up going to Arkham after killing a few prisoners, which is when they lost touch, and Gaggy is convinced that Joker simply became a mean sullen creep during that time. Harley interrupts the story to say Joker called those his “what was I thinking?” years. Gaggy goes on with his trip down Memory Lane, mentioning he always hated Robin but isn’t sure why. I guess we’re supposed to think he recognized Dick on some level. Gaggy’s plan is to disguise himself as Joker and commit crimes like “the old days.” Of course, there was no Harley in the old days, so she has to go. Meanwhile, Catwoman and Poison Ivy are trapped by Gaggy's closing walls. The other two Sirens show up with Jenna the carpenter to the villains, and provide enough distraction for Harley to free herself and send Gaggy off on one of Joker’s old toy rockets. Driving back to the hideout in Jenna’s van, Harley reflects on Gaggy being a version of her and her obsession with “Mistah J.” She asks “Do I really come across that lost and needy when I talk about Mr. J?” Catwoman says, “Absolutely.” Ivy also says, “Totally.” Jenna also says, “I just met you and I’d have to say yes.” Harley says she’s done with the Joker, but then starts backsliding at once, noting well this wasn’t the real Joker. Ivy gags her with a vine, Selena thanks her, and Gaggy crashes in Gotham Harbor, saying “Next time, Quinn,” as he climbs out.