"You die at first light!" -- 101 reasons not to kill captive PCs straight away

[Asmor]

27. Killing a prisoner is taboo. Instead of execution, the local custom is to toss them down a sinkhole with no supplies or equipment and then grant them pardons. Opportunistic carnivores await.

 

[Kaodi]

28. You want to dispose of some of your rivals or underlings, but killing them outright would make you unpopular with the rest of them or your organization. So you arrange for them to be guarding the prisoners path to freedom when they make their inevitable escape attempt (which you have also stealthily enabled).

 

[darjr]

29. There is this new dungeon we are building, it needs proofing

 

[haakon1]

30. Junior needs some easy experience points/street cred with the tribe. He can't get full XP/credit if they are totally banged up, so let them heal a little, then he'll finish them.

31. Waiting for the tide to come in and drown them. "For liability purposes, it's the ocean that killed you." -- a paraphrased line from the Simpsons where they are kidnapped by pirates (modern ones, from the "secret pirate island" of Hong Kong, not Disney-style).

 

[Kaodi]

32. Your god has only a handful of followers. As he cannot be sure of a steady stream of sacrificial victims, he demands that you do not squander potential sacrifices by killing them all at once.

 

[Kaodi]

33. The characters interrupted dinner and if you spare the time to finish them off now it is going to get cold.

 

[Dannyalcatraz]

34) Evil overlord trying to prove to his fiancee that he has a merciful side.

 

[DanotheSlender]

35. they are to be sold into slavery.
36. they are to be guinea pigs for all the magic items you failed to identify properly.
37. they are attractive specimens, except for they are male...now where is that girdle of masculinity/femininity...
38. dragon (insert any carnivorus beastie you may be huntin) bait.

 

[Darkness]

39. They are going to be given a chance to convert to their captors' religion in exchange for their lives. Of course, not just anyone is qualified to convert unbelievers; such a task requires a competent recruiter, who will return in a few days.

 

[Stormonu]

40. They are to be forced to watch the villain destroy everything they care about - then they will be given the permission to themselves die.

41. We need entertainment for the troops. They get to fight each other to the death over the next few days.

42. I have this "inescapable" death trap I want to try out.

43. There's something in my basement I need cleaned out/retrieved. Sadly, so far no one's been successful...

44. We've got an opening or two in my organization; you've been selected for try-outs.