Replicator systems are a class of first order, nonlinear differential equations, arising in an extraordinary variety of modeling situations. It is shown that finding the stationary points of replicator systems is equivalent to solving a nonlinear complementarity problem. One consequence is that it becomes possible to use replicator systems to solve very large instances of the NP-complete graph bisection problem. The methodological and philosophical import of their equivalence with complementarity problems (upto stationarity) is discussed.