Information holder an object designed to know certain information and provide that information to other objects.
Structurer an object that maintains relationships between objects and information about those relationships.
Service provider an object that performs specific work and offers services to others on demand.
Controller an object designed to make decisions and control a complex task.
Coordinator an object that doesn’t make many decisions but, in a rote or mechanical way, delegates work to other objects.
Interfacer an object that transforms information or requests between distinct parts of a system.