Who was the leader of the T-Birds?

I'd say Danny was the leader with Kenickie a close second.

Kenickie was the leader

I would say Danny is... if you looked at the beginning, Kenickie seemed like the cool one that the other dorks looked up to, but then when they saw Danny, they all flocked to him because he's the cooler one who would naturally be the leader. Kenickie was probably the guy who wanted to be the leader and almost had it in him but in the presence of Danny he falls short... sort of like how Starscream always tries to overthrow Megatron in Transformers.

I always thought they were co-leaders?

"I must express myself." - Delia Deetz

Kenickie is definitely the leader. If you see the play it's more obvious in some scenes that aren't in the movie.

Danny and Kenickie were the "cool dudes". Doody, Sonny and Putzie were three dorks looking for something to belong to.

In the play, Danny was the leader of the Burger Palace Boys.

In the movie, it seemed that Kenickie was the leader of the T-Birds while Danny was the second-in-command.

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