Doctor Who: Who Is Ruby Sunday, the Doctor's New Companion?

The Doctor Who Christmas Special has aired, marking Ncuti Gatwa's first full episode as the Doctor, and introducing the Doctor's new companion Ruby Sunday, played by Millie Gibson. But who is Ruby Sunday? Here's what we learned about Ruby Sunday in the Doctor Who Christmas Special, "The Church on Ruby Road." SPOILERS follow for the Doctor Who 2023 Christmas Special, "The Church on Ruby Road." The Doctor Who Christmas Special begins by revealing that Ruby t is a "foundling," a child left on the steps of the titular church on Ruby Road. As an infant, Ruby was handed over to a foster mother, who eventually adopted her. She still lives with her adoptive mother and grandmother today.

The Doctor begins observing Ruby from afar and eventually introduces himself. They then end up on an adventure as they try to rescue a kidnapped baby from time-traveling goblin pirates. The pirates try to erase Ruby from history by going back in time to steal her off the steps of the church, but the Doctor travels back in time to set things right. At the end of the episode, Ruby heads into the TARDIS to begin her adventures with the Doctor, but some questions still linger.

Who is Ruby Sunday on Doctor Who?

The obvious question that viewers will have is about Ruby's parents. Who are they and why did they leave Ruby at the church? In theory, there could be a mundane explanation, but it is curious that the host of a Who Do You Think You Are? style show isn't able to find a trace of Ruby's birth family anywhere. The Doctor could have solved this mystery while he was in the past but chose not to. Whether that's because he knows something about Ruby or because he was simply afraid of messing up the timeline is unclear.

Then there's Ruby's neighbor, who seems to know more about the Doctor than an average citizen should, speaking directly to the audience about the TARDIS. Is this just a cute bit of a fourth-wall-breaking, or is there something more going on? Could this be one of the Toymaker's minions or the Master reborn? An undercover UNIT agent, or something else entirely? It's impossible to know at this point.

Who plays Ruby Sunday on Doctor Who?

The Doctor Who Christmas Special introduces Millie Gibson as Ruby Sunday. "Whilst still being in total disbelief, I am beyond honored to be cast as the Doctor's companion," said Gibson when the BBC announced her Doctor Who casting. "It is a gift of a role, and a dream come true, and I will do everything to try and fill the boots the fellow companions have traveled in before me. And what better way to do that than being by the fabulous Ncuti Gatwa's side, I just can't wait to get started."

Gatwa added: "Millie just is the companion. She is full of talent, strength, she has a cheeky sparkle in her eye and is sharp as a razor. From the moment she walked into the room she captured all of our attention with her effervescence and then solidified that attention with the sheer torque of her talent. This adventure is going to be so wild and so fun, I cannot WAIT to sail the universe with Millie!"

When does Doctor Who return?

The Doctor Who Holiday Special followed David Tennant's run as the Fourteenth Doctor in three Doctor Who 60th-anniversary specials. Gatwa and Gibson's debuts in "The Church on Ruby Road" leads into Doctor Who's new season, its first streaming on Disney+. That season will debut in Spring 2024.

The new season of Doctor Who should be a good jumping-on-point for new Doctor Who fans. Anyone looking to catch up on modern Doctor Who should check out our Doctor Who streaming binge guide.