Which Characters Are Missable?

There are only two characters you can miss without being able to backtrack:

• Kiwi: is the first 'missable' character in the game. If you don't talk to him before the princess is captured, you can never get him again.

• Skreech: is the second 'missable' character. You need to save him when he's just a baby in the flying village - otherwise he'll die a terrible death.

There are 5 characters who are optional:

• Karna, Randolf, Tyrin, Eric: One of these four characters you must select - but the other three are available once you defeat the Greater Devil Cameelia.

• Sheela you can miss if you don't spy on her while she's bathing. You can always go back to get her though (she bathes for a long time).

• Claude is the golum who can't walk because he has a missing arm (wait, what?) Give him his arm and he'll walk again and join the force.

Finally, there are three characters who are in plain sight who are technically 'missable' (but you can always backtrack to get them):

• May - She's right at the entrance in a village but if you don't talk to her - she won't join you.

• Taya - If you don't talk to her statue, she won't join you.

• Chaz - If you don't play the piano, she won't join you.

There is Sheela I believe, a Master Monk we can find way later in the game
There is Golem, and we need to find the hand of Golem as well before we can talk to him
All the characters we we don't choose at Creed's mansion at first are also expendable
Also there is Chaz, whom we need to play a piano to meet
I don't remember the exact details, but the only optional character that is in plain sight is the tortoise in the first stage
The others require us to find some secret item or do some obscure task or go to a place we wouldn't normally visit
Also, this might help