Taylor Swift accepts the award for tour of the year...

Taylor Swift accepts the award for tour of the year at the American Music Awards on Oct. 9, in Los Angeles. Credit: AP / Invision / Matt Sayles

Pop star Taylor Swift held a star-studded New Year's Eve costume party, with guests including actor couple Blake Lively and Ryan Reynolds, and model Gigi Hadid. Swift dressed as Ariel from the animated feature "The Little Mermaid."

"Mary Poppins, Audrey [Hepburn], Ariel, Ms. Frizzle [from TV's "The Magic School Bus"], Cinderella, Gwen [Stefani], Mr. Toad [from "The Wind in the Willows"], Avril [Lavigne], Nancy Drew, Posh Spice, [Betty] Rizzo [from the musical "Grease"], Frida Kahlo, Steve Irwin, Dorothy [Gale from "The Wizard of Oz”].. This new year we decided to dress up as our childhood heroes," the 29-year-old Swift wrote on Instagram, captioning the first of four photos in a set.

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Pop star Taylor Swift held a star-studded New Year's Eve costume party, with guests including actor couple Blake Lively and Ryan Reynolds, and model Gigi Hadid. Swift dressed as Ariel from the animated feature "The Little Mermaid."

"Mary Poppins, Audrey [Hepburn], Ariel, Ms. Frizzle [from TV's "The Magic School Bus"], Cinderella, Gwen [Stefani], Mr. Toad [from "The Wind in the Willows"], Avril [Lavigne], Nancy Drew, Posh Spice, [Betty] Rizzo [from the musical "Grease"], Frida Kahlo, Steve Irwin, Dorothy [Gale from "The Wizard of Oz”].. This new year we decided to dress up as our childhood heroes," the 29-year-old Swift wrote on Instagram, captioning the first of four photos in a set.

"Sending you all love and hope going into 2019," she added. The main image shows 14 women in costume, on and around a stairwell at an undisclosed location.

Hadid, 23, posted an Instagram close-up of herself as Mary Poppins — styled closer to the Emily Blunt version of "Mary Poppins Returns" than to the Julie Andrews version of 1964's "Mary Poppins" — and wrote, "Just a spoon full of sugar helps 2018 go down ... in the most delightful way! HAPPY NEW YEAR !"

Lively, 31, came as Dorothy Gale, complete with a dog mannequin in a basket to represent Toto. Her husband, "Deadpool" star Reynolds, 42, is dressed in a suit in the last of Swift's four photos, in which he and Swift each drink from a bottle of Aviation Gin, the spirits company of which he became part-owner in February.

The party was held in New York City, according to reports, but the venues pictured on the Instagram posts were not identified.

Copious media outlets identified others in the photos as Abigail Anderson Lucier, Swift's friend since high school, portraying Victoria Beckham as her stage persona Posh Spice; Maude and Iris Apatow, the actress daughters of Syosset-native filmmaker Judd Apatow, as, respectively, artist Kahlo and fairy-tale figure Cinderella; and stylist Ashley Avignone as pop star Stefani.

Swift's acclaimed "Reputation Stadium Tour" special debuted on Netflix on Dec. 31.