Greatest Intro Song?

By this I mean first song that likely would’ve been heard from a band or artist in their career, which often would be the first song off their debut album. For my taste, two examples which immediately come to mind would be:

Do It Again - Steely Dan 21st Century Schizoid Man - King Crimson

But I’d love to know what other songs would fall into such a category, so what song would you nominate?