Punchline is the Joker's new right-hand woman.
Alexis Kaye was a student of Snyder College when she had her first encounter with the Joker while on a field trip at a TV studio. Joker had hijacked the studio and forced Alexis at gunpoint to act as a newsreader and deliver his 'message' to the citizens of Gotham. The stunt was interrupted by Batman and Alexis was saved, but she developed an obsession with the Joker. She quickly came to believe that the Joker's crimes served a greater purpose.
She started an online podcast dedicated to the Joker and thoroughly researched all of his past crimes. Eventually, she created her own costume and began poisoning people around Gotham to attract the Joker's attention. He saw potential in her and taught her how to create a modified form of Joker Venom, which she used to experiment on the homeless community.
The college's dean Bob was concerned with Alexis' behaviour and went to talk to her, but she murdered him with her form of Joker Venom, before finally adopting the persona of Punchline and thus successfully proving herself to the Joker.
Road to Joker War
Punchline was hired as a new underboss by the Joker in lieu of his coming war against Batman after Superman revealed his secret identity to the world, and Joker decided that a final battle with Batman using his secret identity in play would be fun. Punchline was at first assigned for a stake-out on Catwoman who had gone to dig up a Joker-lookalike's corpse after receiving a message from the Designer, not knowing it was the body of the Joker's gang member Artie. Punchline informed the Joker about Catwoman and Harley Quinn having found Artie's body, but he stated it was okay as he had to meet a few people first.
During Lex Luthor's battle against The Batman Who Laughs, Punchline held Mercy Graves hostage while Joker dealt with Lex for using the help of the Dark Multiverse's Batman despite his warnings. Joker however let both go, stating it was a joke all along and Lex had got what he needed.
She encountered Catwoman and Harley Quinn while working with Underbroker and fought Harley. Punchline cut Harley's neck and ordered her body to be dumped into the river. She then wounded Catwoman and used the account numbers Catwoman had stolen to steal the entire Wayne fortune from Batman for the Joker.
With Joker in control of the Wayne fortune and Underbroker in control of Wayne Enterprises, Punchline went in to capture Lucius Fox, poisoning him to take control of Batman's equipment. When Batman returned to the building, Punchline was waiting for him, catching him by surprise with the new Batsuit Lucius had designed for him. Punchline mocked him for losing everything and infected him with a hallucinogenic version of the Joker Serum, forcing Batman to flee.
At Tricorner Yards, Punchline and Underbroker doublechecked the arriving shipments of chemicals so they could make a larger batch of her Joker Serum variant. They learned of a clown-themed vigilante, Clownhunter, attacking Joker's gang members, but Punchline forced Joker's goons to get over it. She warned Joker of Clownhunter and Batman's continued existence, but he was unworried, telling her to send some of his tougher thugs to take care of Clownhunter before going off to kill Harley Quinn.
Finding Harley Quinn and Batman in Eden, a forest area hidden underneath Gotham that Poison Ivy made for Harley, Punchline proceeded to try and torch the place before Harley shot her with a flamethrower. As they fought, Punchline taunted Harley for ever believing she could reach the Joker's heart. When Punchline said the Joker truly loved her for "understanding" him, Harley lashed out, telling her that he's nothing more than a manipulator and she's just his latest victim, and that all he cared about was Batman. Furious, Punchline broke away, ready to kill Batman to prove her point. However, she arrived just as Batman had broken free of her drug thanks to a concoction Harley had given him earlier. Her defeat at Batman's hands was quick.
- Hand-to-Hand Combat (Basic)
- Weaponry: Punchline wields two daggers which she uses with skill. She was able to seriously wound Harley Quinn and injure Catwoman in her first fight against them.
- Punchline's creator James Tynion IV revealed her last name was "Kaye" in an IGN interview before it was officially confirmed within a series. 
- James Tynion IV has stated that she is intended as an anti-Harley Quinn, being a silent and intimidating serial killer and the fact that the Joker seems to actually care about her.
- 25 Appearances of Alexis Kaye (Prime Earth)
- 56 Images featuring Alexis Kaye (Prime Earth)
- 1 Quotations by or about Alexis Kaye (Prime Earth)
- Character Gallery: Alexis Kaye (Prime Earth)
- Punchline #1
- The Joker 80th Anniversary 100-Page Super Spectacular #1
- Batman (Volume 3) #85-89
- Batman (Volume 3) #89
- Year of the Villain: Hell Arisen #3
- Batman (Volume 3) #92
- Batman (Volume 3) #93
- Batman (Volume 3) #95
- Batman (Volume 3) #97
- Batman (Volume 3) #98
- Nightwing (Volume 4) #72
- Nightwing (Volume 4) #73
- Rich Johnston (February 17, 2020). 'Punchline Should Be The Devil' – James Tynion IV and Jorge Jimenez's Designs on Joker's New Girlfriend. Bleeding Cool. Retrieved on March 26, 2020.