Serena Casey said:
I did - there was one in Boston (there were two others, one from Canada and one from the UK). Does that mean I can't use it? I know band names can't be copyrighted but could be trademarked, but I don't know if that applies when the band is fictitious.
Absolutely not! A band can no more copyright a name than a writer can copyright a title, and certainly there are thousands of bands playing across the country even as I write this who are playing under the same name as some other band from somewhere else. Two things you would want to avoid, of course: You probably would not want to use the same name as a band that's fairly well known or unique. I guess this is what you meant by bands that have trademark names. For example, you wouldn't get away with calling a fictitious band The Beatles or The Rolling Stones because those bands pretty much have a monopoly on those names, and other huge names, like Pink Floyd, The Doors, The Who, Led Zeppelin, etc, are just too firmly identified with those particular bands. But with a generic name like, well, Firefly, I would say you really have nothing to worry about because none of those real-life bands you mentioned are big enough or well-known enough to have an exclusive on the name. (Obviously, if they were, there wouldn't be at least four identifiable bands currently using the name).
Another caution is to make sure no one you are writing about can be too clearly identified with someone who might actually be in a real group by that name. Of course, realistically you probably can't screen every band going by the name of "Firefly" out there, but just make sure your characters are fictionalized enough that no one would even think about drawing a comparison between your fictional band and their real-life one.
I really appreciate the input so far - thank you guys.
