Michael John Rinder (/ˈrɪndər/; April 10, 1955 – January 5, 2025) was an Australian and American former senior executive of the Church of Scientology International (CSI) and Sea Org based in the United States. From 1982 to 2007, Rinder was on the board of directors of CSI and also held the post of executive director of its Office of Special Affairs, overseeing the corporate, legal and public relations matters of Scientology at the international level.

Rinder left Scientology in 2007. Since then he talked about the physical and mental abuse inflicted upon staff members by the leader of Scientology, David Miscavige, and by Rinder himself before his departure from the organization. He also stated that abuse was embedded into the culture of Scientology. From 2016 to 2019, he co-hosted the Emmy Award-winning A&E documentary series Leah Remini: Scientology and the Aftermath. In 2020, he and Remini reunited to launch the podcast Scientology: Fair Game. In September 2022, he published a memoir titled A Billion Years: My Escape From a Life in the Highest Ranks of Scientology.

Rinder was born in Adelaide, South Australia, on April 10, 1955, to Ian and Barbara Rinder. When he was 5 years old, his parents became interested in Scientology and the family began attending the Church of Scientology International center in Australia.

In a 2006 interview with Rolling Stone, Rinder said he had experienced discrimination in Australia during the period when the state of Victoria had banned Scientology: "You couldn't own Scientology books ... If you did, you had to hide them because if the police came and found them, they'd take them away."

After finishing high school, at age 18 Rinder joined Sea Org on the ship Apollo, then headquarters for Sea Org and for Scientology. He became an early member of the Commodore's Messenger Organization and rapidly rose in rank to head of the Office of Special Affairs.

As executive director of the Office of Special Affairs (OSA), Rinder was the chief spokesperson and representative of Scientology to the media for 25 years until he was replaced by Tommy Davis as spokesperson in 2005 under orders from David Miscavige. This office is responsible for overseeing public relations and legal issues for the church, as well as handling "internal investigations into members' behavior."

In a 2016 Rolling Stone recap of the second episode of Leah Remini: Scientology and the Aftermath, Rinder said of his position:

If the Church decided someone was an enemy and needed to be silenced or destroyed, it was my job and I did it ... Everything from following them 24 hours a day to having people camped outside their door, to being vilified on the internet, to following them wherever they traveled, I was the guy [that did it].