Solo Hakkar?

[Tzuma]

Definitely doable, ive done it with both my pally (with bat up), and my DK (with everything dead). I was actually forced to solo it with the DK because in attempts with friends (2-3 others) and the MC made it impossible.

[Er4t4y]

killed him 1sec before enrage using only Shield of righteousness rank 2
used some ret gear SoW and JoW all the time.
loh at 50% mana pot at 20% normal tanking spec
497def, 1114BV, 23melee crit, 2500ap, 14% spell crit

[Deloimoi]

Ive done it easy when I was a feral druid, tried it as resto but couldn't beat the berserk timer (I think I got him to like 450k hp before he owned me). My feral gear is mostly crafted epic/heroic gear.

[Tropicana]

Before the double SoR nerf, I could kill him in 7 minutes, in ret gear. I hadn't tried since the nerf until yesterday. Again, in ret gear, still had about a minute left.