David Tennant's Doctor will take centre stage in three specials we previously learned will be titled "The Star Beast," "Wild Blue Yonder," and "The Giggle."

Source: https://comicbookmovie.com/tv/bbc-america/doctor-who/doctor-who-trailer-for-60th-anniversary-specials-reveals-donna-nobles-fate-and-the-celestial-toymaker-a205823

In an episode of the time-travelling BBC show called The Giggle, the Scottish-Rwandan actor was unveiled for the first time on Saturday night (December 9).

Source: https://www.heraldscotland.com/news/23980280.ncuti-gatwa-doctor-actor-edinburgh/?ref=rss

In "The Giggle" (directed by & written by Davies), the giggle of a mysterious puppet is driving the human race insane.

Source: https://bleedingcool.com/tv/doctor-who-the-giggle-promo-the-doctor-faces-one-final-game/

In "The Giggle", the Toymaker tells the Fourteenth Doctor that, as part of their game, the Master wagered on being trapped inside the Toymaker's gold tooth if the Master were to lose the game that caused the Doctor's history to be altered so severely.

Source: https://screenrant.com/doctor-who-timeless-child-retcon-toymaker-explained/