Looking at imdb, and guessing on some of his roles, I think Michael Ansara has played every ethnicity except his own (Syrian) - various Mexican and Hispanic, Native American, Egyptian, Sikh, Chinese, Babylonian, Hawaiian, Samoan, Albanian, Italian, generic Arabian, plus generic Caucasian. And, of course, Klingon (boney and non-boney)…
And as for the casting of Montalban, "All Sikhs are Sings, but not all Sings are played by turban wearing Sikhs.”