I think it is Matt Haughey.
He built
OpenDNS, which single-handedly
killed Google Answer (or what is that called again..?).
His community building tips are timeless, sounded and practical.
More about him:
Matthew Haughey - Wikipedia, the free encyclopedia
His classic posts on building an online community:
Digital Web Magazine - Building an Online Community: Just Add Water
Some Community Tips for 2007 | fortuitous
I especially like his tips of "become the community best member" and "forbidden the word - user-generated content".
Who is your master of building an online community?