Designated or chosen by oneself rather than by due authority: a self-appointed mediator. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "self-appointed" in a sentence
"But literature isn't a "dialogue" monitored by self-appointed arbiters who decide what part of the conversation deserves a prize for its insight."
"Advocates of Intelligent Design have become accustomed to critics who tout themselves as defenders of science; self-appointed protectors of children from the dangerous idea that the universe, and life on earth yield clues indicating design and intent."
"Not helping matters is their newly self-appointed spokesman:"