The Birthday Boy was an exclusive comic story included in a special Blu-ray giftset to celebrate Doctor Who's fiftieth anniversary in 2013, produced by the team behind the then-current Doctor Who comic book series by IDW Publishing. It was later reprinted in 2016 by Titan Publishing Group in The Eleventh Doctor Archives Vol. 3, part of a series of reprints of the IDW stories.
Clara Oswald wakes a groggy Doctor with breakfast in bed, telling him that it's his birthday, but things aren't right. He and Clara live in an ordinary house, he has an office, and Clara is preparing well-cooked food for his birthday party. In the Doctor's office, however, is something resembling the TARDIS, which the Doctor vaguely remembers. Out shopping for items, he meets people who are strangely familiar to him — Sarah Jane Smith and the Brigadier, Tegan, Nyssa and Adric, Steven Taylor and Dodo Chaplet, and starts to realise that things are not right. The shops themselves are stocked with curious items such as Adipose and Cybermen, and then the Doctor encounters a band of old adversaries who all ask him for help. Back "home", when he arrives, the Doctor's friends celebrate his birthday. They present him with presents — his fob watch, the TARDIS key, psychic paper and the sonic screwdriver. These items allow him to break free of the mental projection caused by a Trylonian Brain Drain machine. The Trylonians want to drain the Doctor's mind of knowledge of the alien species he's encountered to advance their plans of conquest. Recalling all his previous incarnations, the Doctor overloads the Trylonian battle computer. Surrounded, the Doctor and Clara prepare to fight the monsters, protect their friends and save the planet — just what they always do, in fact.
This is the first time that River Song appears in a comic story in her third incarnation. Her first comic appearance was in her second incarnation, in Imaginary Enemies.
For reasons unknown, the opening page which resembles a birthday party invitation identifies Clara as "Clara Oswin", even though TV: The Bells of Saint John confirms the original Clara's name does not include Oswin.