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May McDuck is a supporting antagonist hero of the DuckTales Reboot episode "The Last Adventure".
She is the twin-sister clone of Webby Vanderquack, who was created by Black Heron.
She was voiced by Riki Lindhome, who also voiced Ginormica from the Monster VS Aliens TV Series.
May is a mall white preteen duck with white feathers that are generally styled in a bobcut. She wears a yellow bow on the right side of her head. She wears a yellow shirt with rolled-up sleeves, a yellow sleeveless sweater vest, and a yellow skirt.
As they invade F.O.W.L's base, Clan McDuck resolves to find the Missing Mysteries of Isabella Finch while Donald, Della, Launchpad, Gizmoduck, and Darkwing set out to capture F.O.W.L. However, the two teams soon determine that the base is virtually empty of personnel, with the Missing Mysteries nowhere to be found. Startlingly, they come across two young Duck girls in a pair of tubes. Upon returning with them to McDuck Manor, they are able to verify that the pair, who introduce themselves as May and June, are in fact clones of Webby.
Beakley forbids the kids to interact with the clones, but Webby is naturally curious about the clones and lets them out of the room where Beakley locks them for safekeeping. Huey, meanwhile, struggles with the failure of the raid against F.O.W.L. that he planned, even snapping at Beakley, who refuses to answer him or Scrooge regarded what she knows about F.O.W.L. Webby shows May and June her room, and the family board, but the two are quick to contradict her statements about her "found family", and question her about her real relatives. Webby admits that she knows next to nothing, as for Lena and Violet walk in just as June is tampering with the board. Causing Lena tosnaps,leaving June running off in apparent tears, making Webby angry at her friend; after going to look for her clone "sister", Webby runs into Beakley.
As Donald and Della go shopping, June goes sneaking into Donald's Houseboat, as she seizes the Sword of Swanstantine that was left there by Della, and is spotted by Huey. When he tries to inform his brothers and Webby, Webby doesn't believe him and becomes hurt, but soon finds confirmation of his words as she finds May stealing the Blessed Bagpipe of Clan McDuck.
May and June admit that they were tasked with obtaining the last two Missing Mysteries, and that Bradford will only answer their questions once they complete their assigned mission. Webby refuses to go along with them, and May takes the two artifacts while tasking June with subduing Webby. The clone gains the upper hand using the potion Webby took from Black Heron, and seemingly subdues Webby.
Webby arrives at the Library of Alexandria, and discovers that Huey has stowed away with them. Still masquerading as June, she leads her "prisoner" into the F.O.W.L.-controlled library, where May is tasked with bringing Huey to Bradford's office.
Webby drags June to a prison cell, as she runs into Steelbeak, Pepper, the Phantom Blot, and Rockerduck along the way. While asking Pepper, she learns the location of the F.O.W.L. archive. Having deposited June in a cell, the disguised Webby enters the F.O.W.L. archive room and begins looking through the records. She discovers that May and June were created using a feather taken from her in Istanbird, the Stone of What Was and water from the Fountain of the Foreverglades, and then discovers a folder labeled "April".
The folder shows a video of Beakley breaking into a F.O.W.L. lab years earlier, but Webby is interrupted by Heron and May before she can learn more about the folder.
However, Beakley's confession causes Webby to realize the depth of her "grandmother's" deception. as Bradford, Heron, May, and June come in, Bradford makes a deal to Webby to know about who she is, leaving Webby to reluctantly agree to help Bradford, her creator, as she was intended to calling her April.
Bradford then seizes the artifact, revealing that obtaining it was the whole purpose of Webby's creation in the first place. When Webby admits that she found it, Ludwig reveals that as May and June were cloned from her, she was cloned... from Scrooge.
After Dewey and Louie save Huey, The Triplets then go on finding Webby only for them, along with Gyro, Gandra, and Ludwig Von Drake to be captured easily by May and June, much to the Triplets' Dismay.
After being captured by The Duo, Dewey tells them to they cannot defeat Webby as she tells them that she is their worst nightmare, only to be revealed to have emotionally defeated Webby tied-up, much to Dewey's dismay. This action is seen by June and May, who realize that their whole purpose has simply been to reawaken a piece of paper. Huey, Dewey and Louie are confused as the Papyrus could only be reused if it ended up in the hands of Scrooge's direct descendant. Drake then reveals the truth: Webby is actually Scrooge's daughter; cloned directly from his DNA. Having learned that their only reason for being was to help Bradford get the last artifact, May and June felt remorse for what they did, but Webby convinces them family is about caring for each other, fighting for them, and helping them that they are then persuaded to help free Webby and the others to save the family, which they are now a part of.
As the heroes try to save Scrooge, the Sword of Swanstantine amplifies Bradford's inner evil into an increasingly monstrous form. He attempts to blast Scrooge, but Donald puts up a barrier and is joined in holding it by Della, Beakley, and the two sets of triplets, including May and June helping them.
Huey and Louie analyze Bradford's contract, and discover a loophole: it says Scrooge can have his family if he gives up adventure; however, as the McDucks always say, "family is the greatest adventure of all". The contract disintegrates, and Bradford loses the sword and is left powerless, fleeing only to find Magica, Glomgold, and the Beagles waiting for him. Magica then turns him into an ordinary Buzzard, and Scrooge's adversaries then depart rather than face his family, both genetic and found. As the whole group heads back home aboard the Sunchaser, Donald speaks on the phone with Daisy and tells her that they should bring them along on their planned trip.