“The Fireflies” from The Last of Us probably being my biggest example but I’m sure there’s others.

It can kind of work in a Fantasy setting cuz it makes more sense for characters in that kind of universe to take inspiration from the natural world (some fantasy novel I read a while back had a rebellion called the “Coyote Army” I think, “Brotherhood without Banner” from GoT is better though), but really in any modern of SciFi setting I think nobody would take a group with a name like that seriously, especially if its the fucking Fireflies.

A clever name can work IF it’s not goofy and there’s a good in universe explanation for it, like in the Lancer RPG setting there’s a group called “The Ungratefuls” cuz the government they’re resisting called the people of their planet “ungrateful” for their rule, but generally just calling them something generic like “The Resistance” or whatever is still leagues better than “The Sparrowhawks” or whatever.