I did it pretty easily with Olaf at around 50 minutes in, items were, 2 Blood Thirsters, 2 Phantom Dancers, Zerker Grieves and a Thornmail. I finished with almost full hp's.

Tryndamere and Ashe are two ive done it with, havent tried it with an AP build champ though.

My build for both was as follows:

Berzerkers greaves
Phantom dancer
Last whisper
Infinity edge
Bloodthirster x2 ((Both thirsters fed))

I ended up doing it and still having full health with both because of the lifesteal

In a practice match I was testing the viability of an AP tryndamere. It was epic. And killing baron at 48 min in by myself was easy. The 1.5 ap on his heal makes it super effective. And he gets full ap on his spinning slash, and since he has some low CD attacks he can use lichbane frequently.

I've done it with Yi, Warwick, and Karthus.

Karthus can, http://www.youtube.com/watch?v=vdFzqGieHu4

Not my vid btw

I've stolen the Baron kill from an enemy team before using Ezreal >.>

Heimer USED to be able to do it... but we all know what happened to him...

I wonder if an AD janna can pull it off?

been doing it consistantly at the 15-22 minute mark with mord if team doesnt feed- its pretty satisfying to hear wtf from enemy when barron buff shows up when the 4 others are beating on towers

if you can get a pet, you can do it at 15 min without madreds- but you still need wriggles/zerker boots