Ben wants to be the biggest boss of the island, and seemed that he had found some way to control Jacob. just like to put some pozzolana around Jacob's cabin. Jacob wants to kill Ben so he makes him has cancer. but god knows in the process of taking John to the island there is a doctor. Jack. Ben knows Locke was Jacob's candidate, and he seemed to know that Jacob can not accuratly control the destiny, so he believed in man is the determining factor in doing things. so he tried to kill John Locke for many times. I think all the answers will be disclosed in the 5th season.

5th season ended in May.

sorry,it should be the 6th season. I typed a wrong number.

Ben kills / wants to kill a lot of people. I'm not sure he has any real important reason for wanting to kill Locke other than jealousy. He's been a dictator on his island, who has has become power crazy and has no problem eliminating people he doesn't like. Goodwin out of jealousy, Caesar out of annoyance, Penelope/Desmond for revenge.

Ben's a psychopath who had too much authority which went to his head

Ana Lucia killed Goodwin when they struggled and she realized he was an other. I wish they'd bring her back instead of claire. hahaha.

Yeah but Ben sent him on a dangerous mission because he wanted Goodwin to be killed. He had the power to order people to their death and he used that power to keep Goodwin away from Juliet. Permanently. Muahahaha.

Ben essentially became what Widmore was banished for. Ben apparently was fond of little trips off-island too judging by the passports, contacts, etc he had. Interesting to see his reaction when he leaves the foot with F-Locke and find sees Dead-Locke spilled out of the crate. I'll be he'll want to stab F-Locke for being had!