Tony Tyler
From Tardis Wiki, the free Doctor Who reference
Tony Tyler was the young child of Jackie Tyler and Pete Tyler and the younger/parallel brother of Rose Tyler.
In the time between the Battle of Canary Wharf and the first journey to Bad Wolf Bay, Jackie had fallen pregnant. (TV: Doomsday) Later, after Tony's birth Jackie jokingly stated that she had named her son "Doctor" to tease the Meta-Crisis Tenth Doctor, before admitting his name was Tony.
Whilst Jackie was fighting the Daleks during their invasion of her Earth, she left Pete on the "nursery run" to look after Tony. (TV: Journey's End)