
The series also announced that Alan Cumming will guest star in the second episode of the season, as the voice of a cartoon character named Mr. Ring-A-Ding breaking out of his celluloid world.
The official description reads: "A bright, funny, sing-along cartoon, Mr. Ring-a-Ding lives in Sunny Town with his girlfriend Sunshine Sally. But in 1952, after years of reruns in movie theaters across the country, Mr. Ring-a-Ding suddenly looks beyond the screen and sees the real outside world - and the consequences are terrifying." Cumming previously guest-starred as King James I in a 2018 episode.
“Only Alan Cumming could give a runaway cartoon so much wit, malice, danger and fun,” said showrunner Russell T Davies. “He makes the whole universe of Doctor Who wilder and madder than ever, and it’s an absolute honour to welcome him on board the TARDIS.” Here’s a look at Mr. Ring-A-Ding:

Cumming joins previously announced guest stars Rose Ayling-Ellis, Christopher Chung, Anita Dobson, Michelle Greenidge, Jonah Hauer-King, Ruth Madeley, Jemma Redgrave and Susan Twist.
The eight-episode season will air weekly from Saturday April 12 on the BBC and BBC iPlayer in the UK and Ireland and Disney+ in the US and elsewhere.