Books on my VERY oversize shelf (Absolutes and Barks Libraries aren't even close):

Golden Age Of Tarzan
Prince Valiant, An American Epic (these are the biggest)
all the Sunday Press books (I think we're up to 5-6 at this point)
The Kat Who Walked In Beauty
Complete Dream Of The Rarebit Fiend

I could probably move a few more that might be big enough - Popeye, Big Ben Bolt/Flash Gordon/Rip Kirby (Austrian editions), Far Side