The Pfaffian quantum Hall states, which can be viewed as involving pairing either of spinpolarized electrons or of composite fermions, are generalized by finding the exact ground states of certain Hamiltonians with k + 1-body interactions, for all integers k ≥ 1. The remarkably simple wavefunctions of these states involve clusters of k particles, and are related to correlators of parafermion currents in two-dimensional conformal field theory. The k = 2 case is the Pfaffian. For k ≥ 2, the quasiparticle excitations of these systems are expected to possess nonabelian statistics, like those of the Pfaffian. For k = 3, these ground states have large overlaps with the ground states of the (2-body) Coulomb-interaction Hamiltonian for electrons in the first excited Landau level at total filling factors ν = 2 + 3/5, 2 + 2/5.