[UPDATE: Stephen Chow is now officially out of The Green Hornet. Bottom of the post for details.]
With Seth Rogen on-board to star, and Michel Gondry attached to direct, the only definite role (beyond an unnamed female role that Cameron Diaz is rumored for) that's still to be filled in The Green Hornet is of his sidekick, Kato. Played in the original TV series by legendary martial artist, Bruce Lee, it had been assumed up until now that Kung Fu Hustle star Stephen Chow was going to be that guy.
This assumption was made because he was once attached to both star as Kato and direct the film - but before long it was announced that he walked away from the behind the camera role, resulting in Gondry coming on-board for directing duties. However, there was nothing to definitely indicate that Chow would not still be playing the sidekick in The Green Hornet.
However, with a recently released casting call for the role of Kato (courtesy of SpoilerTV), Chow's involvement looks like it may be dubious:
"[KATO] ALL ASIAN ETHNICITIES, Male, 20's - early 40's. Brit Reid's manservant/chauffeur by day and Green Hornet's martial arts-skilled sidekick by night sptv050769. Actor doesn't have to have Martial Arts experience."
Out with the debate over just why the casting call is so vague and unspecific - the huge age gap, the indifference to whether the actor needs martial arts experience for a role that involves martial arts - the general question arises of why would they even put out a casting call if Chow was going to be playing Kato?
With the direction they seem to be going with for The Green Hornet movie - that is, action mixed with comedy - I would say that Chow is the perfect candidate to portray Kato. He has martial arts experience (again, I really don't know why the casting call doesn't call for this specifically), he can do the action-comedy thing (just look at Shaolin Soccer and Kung Fu Hustle), he's got great charisma for what I imagine this modern take on the character is going to call for, and I also think he and Rogen would be a good fit. I really hope this casting call is just a precaution, and Chow eventually does play the role of Kato.
UPDATE: Well, no such luck. Stephen Chow is now OFFICIALLY off of The Green Hornet due to scheduling conflicts.
Here's what Columbia Pictures had to say about Chow's departure from the film:
There was a mutual and amicable decision by both sides to move on...We are out now to cast a new Kato and remain fully committed to Michel Gondry's exciting vision for the film, which will begin production this September."
Since Chow is no longer in the role, who else would you like to see play Green Hornet's sidekick?
The Green Hornet is slated for a release on July 9th, 2010.