Well I can't think of everyone he's killed but there was Eko who he only killed after Eko refused to repent and said he wasn't sorry for the things he'd done.

Trying to remember who else was killed by the smoke monster The pilot, in the pilot

Jacob is a manipulator though if his interactions with the Lost people in the season 5 finale really had some bearing on their lives. He gave Saywer the pen to write that letter, made Kate think she could get away with theft and being a horrible actress, did something to Jack and the other ones but I've forgotten what it was.


But the main reason I think fake Locke could be the good guy (or they're both not totally all good or all bad) is that it seems a bit too simple for him to be the bad guy. They always try to surprise people even though its usually not that surprising.

In the other life some people are better off but some aren't, Rose has cancer, Charlie still a drug addict, John still paralyzed for the moment although he doesn't seem that bad off.