The open access movement is really many related movements. Some focusing on specific content types like open access journal articles, open data or open educational resources. Others focused on infrastructures like open courseware, open repositories, open standards, or even the legal framework for open content sharing like Creative Commons.
Keywords: open access publishing, open peer review, open data, open courseware, open educational resources (OERs), open source software, open repositories, open knowledge, open content licenses, open standards, open metadata, open science, open government
Right to Research Coalition (Student-led groups from around the world: “Access to Research is a Student Right”)
SPARC Europe (advocating change in scholarly communication for research and society)
SPARC (Scholarly Publishing and Academic Resources Coalition) North America (early advocates for OA for publicly funded research)
Creative Commons: "when we share, everyone wins" (promotes methods to "legally share your knowledge and creativity to build a more equitable, accessible, and innovative world")
OAD: Advocacy organizations for OA (goes beyond providing OA to other means of promotion)
Author's Alliance ("promotes authorship for the public good by supporting authors who write to be read")