Johnny Depp as Tarrant Hightopp, the Mad Hatter Louis Ashbourne Serkis as a young Tarrant Hightopp Anne Hathaway as Mirana of Marmoreal, the White Queen Amelia Crouch as a young Mirana Mia Wasikowska as Alice Kingsleigh Helena Bonham Carter as Iracebeth of Crims, the Red Queen. Leilah de Meza as a young Iracebeth Sacha Baron Cohen as Time, a powerful Father Time-godlike human clockwork hybrid who speaks in a German accent and rules over of time in Underland using the Chronosphere in his castle Rhys Ifans as Zanik Hightopp, the Hatter's father Matt Lucas as Tweedledum and Tweedledee Lindsay Duncan as Helen Kingsleigh, Alice's mother Leo Bill as Hamish Ascot, now "Lord Ascot" following his father's death Geraldine James as Lady Ascot, Hamish's mother Andrew Scott as Dr. Addison Bennett, a cruel psychiatric doctor Ed Speleers as James Harcourt, an employee of the Ascots Richard Armitage as King Oleron, Iracebeth and Mirana's father Hattie Morahan as Queen Elsemere, Iracebeth and Mirana's mother Joanna Bobin as Lady Alexandra Ascot, Hamish's wife Simone Kirby as Tyva Hightopp, the Hatter's mother Joe Hurst as Bim Hightopp Oliver Hawkes as a young Bim Hightopp Siobhan Redmond as Bumalic Hightopp Frederick Warder as Poomally Hightopp Eve Hedderwick Turner as Baloo Hightopp Tom Godwin as Pimlick Hightopp

Answer this question based on the passage: who played the mad hatter in alice through the looking glass? Let's have some stream of consciousness first.
To answer the above question, the relevant sentence is: Johnny Depp as Tarrant Hightopp, the Mad Hatter So, the answer is Johnny Depp.