When speaking of the known, you're actually speaking indirectly of the knowers.
So if you wanted to speak of present knowers, use is. If you want to speak of knowers in the past, use was.
In his day, Charlemagne was known as a ruthless military leader.
Charlemagne today is known as the uniter of much of western and central Europe in the early middle ages.
So with Bruce Lee you could speak of audiences when he first came on the scene and had yet to establish his reputation, or of audiences when he was alive and had established his reputation, or of his reputation among audiences today, and your tense could change.
Bruce Lee was known as an up-and-coming actor with martial arts expertise.
Bruce Lee is known as a late actor and kungfu master.
Bruce Lee had long been known as a kungfu master until it was disclosed that his fight scenes were done using CGI. just as an example