Ncuti Gatwa (in-universe)

On the cover of an issue of Doctor Who Magazine, there was the picture of a dark-skinned man with short white hair. (NOTVALID: The Daft Dimension 579)

Behind the scenes
Seemingly coincidentally, another dark-skinned man with short white hair, dressed in an outfit resembling that of the Fourth Doctor's, appeared in promotional material for the Eve Online crossover with Doctor Who, The Interstellar Convergence. However, this is likely a coincidence given that no individual resembling these men has ever been in Doctor Who. It heavily suggests the identity of this man is in fact that of the star of the previous issue Cover, as they had appeared on the front a month prior.