"Vecna: Hand of the Revenant" is by Iron Hammer Graphics, with the art being done by Kevin McCann and the story being written by Moddi Thorsson. The official website for the graphic novel was at www.cultofvecna.net but it seems that it's gone now...not that it was anything except a single graphic with an "under construction" banner before.
I had the luck of purchasing this during its debut at GenCon 2002, when the artist and writer were there selling copies. It tells the story of young Vecna growing up (mostly his childhood with his evil, but loving, mother, her death, and his coming back to the city of his youth, Fleeth, to destroy it).
While visually spectacular, and an excellent read, the graphic novel is definately non-canon. It says that Acererak was a disciple of Vecna (something Moddi, IIRC, said was inspired by a pic in the original Tomb of Horrors seeming to be of Vecna's hand-and-eye symbol). It also has Vecna losing his hand and eye, not at the hands of Kas, but instead due to an attack of holy energy from the clergy of Fleeth. Also, it has Vecna meeting The Serpent for the first time as a young boy, which is questionable.
During my meeting with Kevin and Moddi (at which I was smart enough to have them autograph my copy), they said this was actually meant to be the first of six such graphic novels about Vecna (hence the cliffhanger at the end of this one), but it seems the deal has long since fallen through, since you can barely find mention of this trade paperback unless you are deliberately looking for it.