Systemic risk describes the phenomenon that dependency adds a specific component of risk to a system or network of (financial) institutions as a whole, which would not be present if the institutions were independent from each other. This paper introduces the concept of systemic risk measures. We describe and study its behavior as a function of the copula, which represents the loss variables of the institutions in the network. Further, we define stochastic order relations on copulas and relate them with systemic risk measures.