Martin Luther. Also not a Unitarian, but you can't say the Protestant Reformation and the nailing of the 95 Theses to the church door didn't have an influence on us...
Roger Williams. Not a Unitarian, but the founder of Rhode Island, proponent of religious tolerance, and a personal hero of mine. "God is too large to be housed under one roof."
I really do think that Matt Groening's UUism should be pretty obvious to anyone who's been paying close enough attention to the religious humor on The Simpsons over the years. No one ever seems to comment on it, however.
There are macros of just about everything -- cats, dogs, Buffy the Vampire Slayer, The L Word. Why not Unitarian Universalism?
Anyone is welcome to create their own LOL UUs. I'll post them on this blog (with credit to you) if you email them to me at la.poetesse.roux(at)gmail(dot)com.