Crabbe
It wasn't like they were even really close friends, really. Crabbe was there to intimidate people, to beat little Hufflepuffs up.
It wasn't like he cared, or anything. The only reason that he had even allowed Crabbe into his gracious presence was because that you could never have too many lackies around to beat up any one who offended him. He was just hired muscle, really. Well, that and because their dads were buddies, always going to Death Eater revels and torturing Muggles in their spare time together.
Crabbe had been blood-thirsty and power-hungry in his final moments, willing to throw away everything for what would've been, inevitably, a few short momments in the Dark Lord's favor, willing to use a deadly curse to create deadly fire that he didn't know how to stop.
Draco Malfoy didn't care, really, he didn't... but that didn't stop the hurt, not really.