My first kill was a giant. We were playing during lunch in high school (it was the late 80's), and we were captured, and made to fight in an arena. The PC's see the doors open on the other end to see a giant and a horde of goblins.
I was playing an elven thief. I ran.
In the end, climbing out of the pit failed repeatedly, and the giant was coming after me, so I drew back my bow, and one crit later there was a dead giant in the pit.
Now, the second creature I killed was a human. I was an elven ranger (I had a thing for elves those days), and I made my way through the castle to the end where the big secret lay. There was one guard. One. I was using a staff, knocked his feet our from under him, then when he wouldnt talk, I thumped him in the throat. I didnt mean to kill him...honest. I just wanted him to talk...