In fairness, a number of the people who have been mentioned here (like Kevin Hart, Jackie Chan, Dirk Benedict) are just celebrities who have been invited to visit City at some point and have been photographed holding up a ceremonial shirt to mark the occasion, but it's all just publicity. There's no real evidence they follow the team, they just have been wrapped up in City PR at some point. The Hoff is questionable, as he's put pictures up on social media wearing his Yaya shirt years after receiving it, but hasn't really done much to suggest he wears it for anything other than he likes the shirt and the player.
However, in order to positively contribute, I will add this: I believe that we can possibly claim the first PM to ever openly support a club. Arthur Balfour, 1st Earl Balfour and Prime Minister from 1902-1905 was a City fan, IIRC because he was persuaded quite early on to be a patron/financial supporter of the club and ended up being a fairly major benefactor.