Bill Compton's middle name ..

In Dead until Dark Bk 1 Sookie dreams that Bill's full name is :

William Erasmus Compton

"Bill," I muttered. I turned to face a stone I hadn't yet touched. When I lay my fingers on it, they traced the letters "William Erasmus Compton." As if I'd been dashed with cold water, my eyes flew open, I drew in a breath to scream, and my throat gave a great throb of pain

In Living Dead in Dallas Bk2 she finds out that his middle name is actually:

William Thomas Compton

I could barely make out the writing.William Thomas Compton,his mother had written, or perhaps his father.Born April 9, 1840. Another hand had written Died November 25, 1868.
"You have a birthday," I said.

Compton family genealogy HERE
Photos -this is the headstone Sookie finds in Bon Temps Cemetery in True Blood.

Nice gravestone image from Lynn, Thanks ! http://lynnpdesign.com/wallpapers