Church of Scientology
Founded in the 1950s by science fiction author L. Ron Hubbard, the Church of Scientology is based upon theories written by Hubbard in his book, Dianetics: The Modern Science of Mental Health. It claims to have 8 million members worldwide, though the claim is disputed. The current head of the Church is David Miscavige, who controls the organization through a complicated system of corporations and committees. 
Unusual for a modern-day church, Scientology has a required donation system which revolves around a complicated set of grades, separated into the Bridge, Clear, and OT levels. 
Members include a number of famous celebrities such as Tom Cruise and John Travolta.
The CoS peak management headquarters is in a secret location. In Clearwater, FL the Church's "Flag Land Base" delivers higher (but not the highest) level training and counselling (called 'auditing') to its members. The Church has come under fire for retaining security guards who are confusingly dressed similar to police officers, as well as having an extensive network of surveillance cameras focused within and without the Clearwater campus. In the past, the Church's Guardian Office (GO) had the mission to protect the Church. It included an intelligence collection branch. The GO was replaced by the "Office of Special Affairs" in the early 1980s. Since the late 1960s, the elite of Church staff called "The Sea Org" (SO) have held the highest level management positions of the Church and its associated groups. The SO is organised similar to naval structure. 
Internet Censorhip and Copyright Issues
The Church has issued a number of lawsuits and cease and desist letters to individuals who have published critical essays about the Church in which the authors often cite CoS material that the Church maintains is trademarked and/or copyrighted. The Internet Archive, as well as Google, have been targets, often in attempts by the Church to silence a very critical website called Operation Clambake (see below). 
Also, the internet access of many of its members is censored via website blocking software that came with a widespread distribution of internet software within the Church's ranks. 
Scientology in Greece
After an extended campaign from Greek Orthodox priest, Father Antonios Alevizopoulos, the government of Greece conducted raids of KEFE's offices. In response to this raid, the Office of Special Affairs, the PR/Intelligence gathering arm of the Church, drew up plans for the 558 program.
In 1997 a Grecian judge ordered the shut down of KEFE's Athens' office, citing the acquisition of non-profit status under false pretenses. 
Scientology giving 'assists' to Tsunami victims
The Church of Scientology is operating in Indonesia with relief efforts, but is controversially not providing regular medical assistance, but rather Scientology's unproven, and unverified mental/physical health techniques. The Volunteer Ministers are not medical in nature. Their help is aimed at bringing spiritual and mental relief from trauma, as well as organizational and logistical help. 
- Lawrence Wright, Going Clear: Scientology, Hollywood, and the Prison of Belief (Alfred A. Knopf, 2013). review
- John Sweeney, The Church of Fear: Inside The Weird World of Scientology (Silvertail Books, 2013).
- Jenna Miscavige Hill with Lisa Pulitzer, Beyond Belief: My Secret Life Inside Scientology and My Harrowing Escape (William Morrow, 2013).
- Association for Better Living and Education (ABLE) is an umbrella organization for Scientology's various secular outreach efforts.
- Applied Scholastics is an organization that uses L. Ron Hubbard's "Study Tech" as a model for child education.
- Citizens Commission on Human Rights describes itself as a watchdog of the psychiatric profession.
- United for Human Rights claims to support the UN Declaration of Human Rights.
- Criminon is a secular organization that uses the drug-prevention methodology of Narcocon (see below) in combination with education and other methods to rehabilitate criminals.
- Narconon is a drug rehabilitation program using the technology and methodology of Scientology. Under fire for being harmful and unsuccessful.
- World Institute for Scientology Enterprises (WISE) is a group of corporations and businesses that follow the management methodology of L. Ron Hubbard.