Kato, sidekick to the Green Hornet was ground breaking in several ways.
Kato brought martial arts and ethnic minorities to USA homes decades before it was fashionable to do so. Kato was more effective than Britt Reid in fighting crime and yet he was content (humble even) to maintain a support role. That is rare in an ego-driven world. His character has stood the test of time in all the formats this duo has been presented: in radio, television, comic books, and movies.
Kato also became the star in the Hong Kong circuit. Not many sidekicks become elevated above the hero while the hero is still around. He was elevated by the populace watching the series, not by his own actions.
Finally, Bruce Lee was the real deal, bringing martial arts to the world of make believe entertainment. There are a lot of good, and a few great sidekicks, but none can match Kato.