Rawandan-British actor Ncuti Gatwa is on the rise with roles in “Sex Education,” “Barbie,” and currently, as the lead of “Doctor Who,” the wildly popular BBC sci-fi comedy series that first aired in 1963. Gatwa’s casting in “Doctor Who” saw the actor face an extreme level of racist backlash, reminding us all over again of the sexism that fellow “Doctor Who” alumni Jodie Whittaker experienced when she was hired to play the Doctor in 2017 (the role has mostly been portrayed by white men so far).