  In this talk I present a simple and unified approach to both exact and
quasi-exact solvabilities of the one-dimensional Schr\"odinger equation. It is
based on the prepotential together with Bethe ansatz equations. This approach
gives the potential as well as the eigenfunctions and eigenvalues
simultaneously. In this approach the system is completely defined by the choice
of the change of variables, and the so-called zero-th order prepotential. We
illustrate the approach by several examples of Hermitian and non-Hermitian
Hamiltonians with real energies. The method can be easily extended to the
constructions of exactly and quasi-exactly solvable Dirac, Pauli, and
Fokker-Planck equations, and to quasinormal modes.
