Introducing seemingly autonomous virtual beings into virtual environments to co-habit and collaborate with us is a continuous challenge and source of interest. Latest proof of human excitement for virtual life is the current worldwide craze for electronic pets that must be fed and cared for lest they develop a bad character or die. Even more interesting is the inclusion of autonomous actors in networked collaborative virtual environments (NCVEs). They provide a meeting place for people from different geographical locations and virtual beings. In NCVEs one doesn't see correspondents, only their graphical representations in the virtual world, which is the same as for the virtual ones-therefore the communication with virtual beings can come naturally. There is no single solution to the simulation of autonomous behavior. This is an ongoing research topic. Therefore it is interesting to provide an open NCVE system for easy interfacing with various implementations of autonomous behavior. In this way, the system can serve as an application platform with existing algorithms, as well as a research testbed for new autonomous behavior algorithms. The paper studies the requirements for such an open interface and, based on this study, presents an implementation within the Virtual Life Network (VLNET) system. Results are presented in terms of two case studies. A simple one implementing a dumb servant character and a more complex one connecting VLNET with the autonomous agent program Eliza (Weizenbaum, 1966)