The very first Dalek story featured Peter Cushing as the Doctor in "Doctor Who and the Daleks" (1965). Excellent origin story for those who have not seen it yet.
Cushing played the first Doctor in 2 feature films, for some reason William Hartnell played the first Doctor on television, but Cushing was selected to play him in 2 films "Doctor Who and the Daleks" and "Daleks - Invasion Earth 2150 AD". Probably because the early years of Doctor Who were sporadic, Hartnell film "An Unearthly Child" in '63 as a pilot. It was likely a case of work schedule conflicts.
I have not watched "Daleks - Invasion Earth 2150 AD" yet, but plan to soon.