>>149751277 (OP)
It's mostly assumed that they're written by ghost writers particularly if it's a mini series. Probably just have some ideas or themes that they tell to the "co-writer" which is then translated into a functional story. Writing comic books is surprisingly involved because you have to coordinate with the artist while dealing with editorial. This is time that most working celebs, particularly if they have to do filming, don't have
The only case where I know the celeb actually wrote the comics was Bemis and it was so shit.