Off the top my head I can remember,
Cinderpelt and her siblings (taken as kits by Brokenstar, although they go unnamed, and there might have been others too
Brokentail
Hollypaw
Twigpaw
Violetpaw
Squirrelflight
Leafstar (twice, if you count the time she was captured by a human and held hostage in her house)
Sol
Firefern (same as Leafstar)
Harrybrook (same as Leafstar)
Stormheart (same as Leafstar)
Frecklewish (got captured in an apartment)
Yellowfang (twice, although once was an act)
Star Flower
Stormfur
Needletail
Mistystar (this happened to her twice and the second time was Darktail’s group; there were others with her, but I don’t remember who)
Cloudtail
Berryheart
Littlecloud
Whitethroat
Bramblestar
There was also cats from all four clans captured by humans and arc two, numerous times when that happened to Skyclan, and one of the main problems WarriorClan has to solve. There’s also a lot of deceased cats who his spirits are being held hostage by Ashfur, but I’m not sure if those count.