Courtney Woods

Courtney Woods was a pupil at Coal Hill School who was taught by Clara Oswald and Danny Pink. (TV: Listen) She was infamously known as a "disruptive influence" and took great pride of her insolence. (TV: The Caretaker)

After being threatened to be kicked out of school by Clara, she replied with, "Go on, do it." Clara was inspired to use the same tactic against the Half-Face Man when he threatened to kill her. (TV: Deep Breath)

She teased the school secretary about Danny. (TV: Into the Dalek)

She once told Clara she couldn't focus on her work because Clara's face was "too wide". Clara related this story to Danny on their first date. (TV: Listen)

Courtney went to fetch some paper towels from the new caretaker - the undercover Twelfth Doctor - and saw a light coming out his TARDIS. He initially denied her knowledge, but then showed her the capabilities of his ship. He took her into space. The experience was too much for Woods, who was made sick by it. (TV: The Caretaker)

Courtney later accompanied the Doctor and Clara on the Moon. (TV: Kill the Moon)

The Doctor suggested to Clara that Courtney eventually became President of the United States and married a man named Blinovitch. (TV: Kill the Moon)

Behind the Scenes
He may have been joking that she would be the second black president/first female president of the US, seeing as he says she isn't special. He would be being sarcastic by implying she would 'be that special.'
 * In the real world, one of the requirements to become President of the United States is to be a natural born citizen. Assuming this requirement also exists in the DWU, the Doctor may have been joking when he told Clara that Courtney would grow up to be President or the requirement might have been lifted by the time she was elected, or perhaps that Courtney was born in the United States but grows up/spends her childhood in England.