I thought Steve McQueen"s debut was in " The Blob " ??
Anyway, I have always been impressed with Michael Caine in " Zulu"--I think (I"M not sure ) that that film was his debut, and his performance,under the circumstances ( he was required to speak with an upper-class accent throughout ) was pretty impressive. At the other end of the scale, I think the WORST debut was Horst Bucholz in The Magnificent Seven . Discuss !!.