Green IT is a mandatory process required for energy consumption reduction and sustainable development. Many actors are involved in the development and adoption of Green IT, ranging from individual persons to research groups, companies, governments, and countries. This chapter identifies actors for innovation in the field of Green IT, explores, and defines them. Their interactions are detailed and their influence on the Green IT landscape is pointed out. A definition of Green IT is given as a common understanding to form a basis for all further investigations of this sector. Then we detail the different actors of innovation in Green IT and outline their relationships to understand the keys for better development and adoption of Green IT.