The Green Hornet and Kato
The Green Hornet and his sidekick Kato aided the dynamic duo against Colonel Gumm in the episodes; "A Piece of the Action / Batman's Satisfaction". The Green Hornet was played by Van Williams. Kato was played by Bruce Lee.
Behind the Green Hornet mask is Britt Reid, the publisher of "The Daily Sentinal" newspaper and long time rival of Bruce Wayne. The only people who know the true identity of the Green Hornet are; the District Attorney, Casey Case and of course Kato. Normal everyday citizens and the police force believe that the Green Hornet is a super criminal but instead he fights crimes and dangerous criminal gangs.
The Green Hornet arrives in Gotham City to get to the bottom of the crimes in the "Pinkchip Stamp Factory" where Colonel Gumm is taking advantage of Miss Pinkston's legit stamp factory to become the centre of his crimes. Commissioner Gordon is alerted by Miss Pinkston who notices the Green Hornet's famous car "The Black Beauty" outside her factory from her appartment window, that the Green Hornet are in town and think that he is causing trouble, so of course Batman is called.
Batman somewhat realises that the Green Hornet is not the trouble maker that everyone believes him to be and does assist him in crimefighting.
The reason why the Green Hornet appeared on Batman was because William Dozier produced the "Green Hornet" television series for ABC whilst the second season of "Batman" was on the aire, the "Green Hornet" ran from 1966 - 1967 only lasting one season. William Dozier used his big sucess with "Batman" to cross-promote the "Green Hornet" television series. The Green Hornet took a more serious stand on fighting crime instead of the fun, witty and camp Batman show.
If you remember, this was not the only time that Green Hornet and Kato appeared on Batman. They both appeared in a batclimb during the episode "The Spell of Tut".
The Green Hornet ABC Promo/Advertisement 1966
I am just going to mention the other main characters who appeared in the Green Hornet television series who did not appear in Batman. On the right is the actor/actress, on the left the character name:
Casey Case - Wende Wagner (pictured above)
Mike Axford - Lloyd Gough
Walter Brooke - District Attorney
William Dozier - Narrator / Producer