He is portrayed by Tosin Cole.
Ryan was born in Sheffield in England between 1998 and 1999 to Aaron Sinclair and an unnamed woman. He was born with dyspraxia. Eventually, Aaron walked out on the family and Ryan was raised by his mother alone. As a child, he attended Redlands Primary School and met a girl called Yasmin "Yaz" Khan.
In 2012 when Ryan was 13, his mother had a heart attack and died. Following this, Ryan was taken in by his paternal grandmother Grace, who worked as a chemo nurse. Eventually, Grace met and started a relationship with Graham O'Brien, who was one of her patients. The couple eventually married, but Ryan had a difficult relationship with Graham and refused to call him his grandfather.
In 2017, Ryan had a meeting with Aaron, but it did not go well.
Role in Doctor Who
In 2018, Ryan (now 19) was attempting to learn how to ride a bike, but struggled due to his dyspraxia. In a fit of rage, Ryan threw the bike into a nearby forest. He goes to retrieve the bike and saw a glowing object and touched it, which caused a large blue object to appear. Ryan phoned the police and was approached by Yaz, who worked for the police. Ryan then gets a phone call from Grace, saying that she and Graham were trapped on a train. Ryan and Yaz go to the train and meet up with Grace and Graham and met the Doctor.
The group later learn that the large blue object was a pod containing an alien warrior called Tzim-Sha, who came to Earth to find a human trophy to take back to his home planet in order to become leader. Ryan helps the Doctor defeat Tzim-Sha, but in the process, Grace is killed. At Grace's funeral, Ryan is annoyed that his father has not turned up.
Ryan along with Graham and Yaz is inadvertently brought along with the Doctor to find her spaceship the Tardis. After finding the Tardis, the Doctor returns Ryan, Gramham and Yaz to Sheffield, but they decide to continue travelling with her.
- Ryan shares similarities with one of the Doctor's previous companions Mickey Smith.
- Both lost their mothers at a young age (Ryan's mother died from a heart attack when he was 13 whilst Mickey's mother Odessa committed suicide when Mickey was 5). Both have fathers who later walked out on them after their mothers deaths (Aaron and Jackson). Both are then raised by their grandmothers (Grace and Rita-Anne). Both also knew another companion of the Doctor in childhood (Ryan went to primary school with Yaz whilst Mickey had known Rose Tyler since they were young (though Mickey was three years older than Rose)).