Moonshine Cohomology Bong H. Lian, Gregg J. Zuckerman Abstract: We construct a new cohomology functor from the a certain category of {\it quantum operator algebras} to the category of {\it Batalin-Vilkovisky algebras}. This {\it Moonshine cohomology} has, as a group of natural automorphisms, the Fischer-Griess Monster finite group. We prove a general vanishing theorem for this cohomology. For a certain commutative QOA attached to a rank two hyperbolic lattice, we show that the degree one cohomology is isomorphic to the so-called Lie algebra of physical states. In the case of a rank two unimodular lattice, the degree one cohomology gives a new construction of Borcherd's Monster Lie algebra. As applications, we compute the graded dimensions and signatures of this cohomology as a hermitean Lie algebra graded by a hyperbolic lattice. In the first half of this paper, we give as preparations an exposition of the theory of quantum operator algebras. Some of the results here were announced in lectures given by the first author at the Research Institute for Mathematical Sciences in Kyoto in September 94.