She continued the role at the Apollo Victoria Theatre until 7 June 2008, being succeeded by Alexia Khadime. Whilst still performing the role of Elphaba, Ellis appeared at the launch of Royal Caribbean International's biggest ship MS "Independence of the Seas" on 30 April 2008, opening its christening ceremony in the ship's theatre with the song "What a Wonderful World" and the British national anthem as it docked in Southampton. She also performed alongside Idina Menzel, Adam Pascal, Josh Groban, Clarke Peters, Marti Pellow and David Bedella in a two-day limited engagement of "" at the Royal Albert Hall on 12 and 13 May 2008. She played the role of Svetlana and upon reflection, stated that to star at the Royal Albert Hall, work with an "amazing" company and sing alongside those particular cast members "was a dream come true." Although a relative unknown and in a small part, Ellis met positive reviews for her performance: a critic labelled her stronger than Menzel – who attained the female lead – and argued that Ellis should have received it instead. This concert version was later released on DVD and CD and screened on US network television. Immediately after her first year-and-a-half long London run as Elphaba, Ellis transferred to the Broadway production of "Wicked" at the Gershwin Theatre with performances starting on 17 June 2008. She replaced stage actress Stephanie J. Block, making her the first "Wicked" actress to transfer from the West End to Broadway – mirroring original cast member Idina Menzel who transferred from Broadway to London. Playing alongside Kendra Kassebaum as Glinda and Aaron Tveit as Fiyero for her five-month run, Ellis won the 2009 Broadway.com Audience Award for Favorite Female Breakthrough Performance. In addition to switching on the lights with "Wicked"'s composer and lyricist Stephen Schwartz at the Empire State Building to celebrate the 5th anniversary of the musical on Broadway, Ellis performed at Broadway on Broadway in Times Square, recorded a song titled "Behind these Walls" for Scott Alan's album "Keys" and released her first extended play (EP) "Wicked in Rock" during her time in New York. Produced by Brian May and Steve Sidwell, the EP comprises three tracks: new orchestrations of "Defying Gravity" and "I'm Not that Girl" from "Wicked" and Queen song "No-One but You (Only the Good Die Young)" that she and May recorded six years earlier.