Carl Sagan was one example: https://thereitis.org/mr-x-by-carl-sagan/ https://thereitis.org/mr-x-by-carl-sagan/ He originally wrote about it under a pseudonym

Carl Sagan was one example: https://thereitis.org/mr-x-by-carl-sagan/ https://thereitis.org/mr-x-by-carl-sagan/ He originally wrote about it under a pseudonym for fear of professional consequences. Many such cases.