William James Ryan (born December 23, 1955 in Moncton, New Brunswick) is a professor of Social Work at McGill University in Montreal, Quebec, Canada. He is an international expert in the field of sexuality, sexual education, homophobia, health and gay men's health. He has conducted research in all these areas, published scientific articles, chapters and edited books. He has spoken at conferences internationally and consulted and trained with many international organizations. He is one of the leaders in the international gay men's health movement and has been a driving force behind the transformation of Action Séro-Zéro in Montréal into a full-fledged gay men's health organization. In 1992 he was the founding president of the Board of Directors of Séro-Zéro, which was founded to undertake H