The presence of complicated local interactions and wave-localization phenomena is generic to a wide range of systems. We show that the statistical properties of these systems can be described by a common mathematical formulation where system information enters through a single parameter. This suggests a possible classification of complex systems in an infinite range of universality classes characterized just by a single parameter and the nature of global physical constraints. It seems to indicate a web of connection hidden underneath complex systems. \\ \\ P.Shukla, Phys. Rev. E, 71, 026226, (2005); 75, 051113, (2007).