Soviet dissidents were people who disagreed with certain features of Soviet ideology or with its entirety and who were willing to speak out against them. The term dissident was used in the Soviet Union in the period from the mid-1960s until the fall of communism. It was used to refer to small groups of marginalized intellectuals whose challenges, from modest to radical to the Soviet regime, met protection and encouragement from correspondents and typically criminal prosecution or other forms of silencing by the authorities. Following the etymology of the term, a dissident is considered to "sit apart" from the regime. As dissenters began self-identifying as dissidents, the term came to refer to an individual whose non-conformism was perceived to be for the good of a society. The most influential subset of the dissidents is known as the Soviet human rights movement.

Political opposition in the USSR was barely visible and, with rare exceptions, of little consequence, primarily because it was instantly crushed with brute force. Instead, an important element of dissident activity in the Soviet Union was informing society (both inside the Soviet Union and in foreign countries) about violation of laws and human rights and organizing in defense of those rights. Over time, the dissident movement created vivid awareness of Soviet Communist abuses.

Soviet dissidents who criticized the state in most cases faced legal sanctions under the Soviet Criminal Code and the choice between exile abroad (with revocation of their Soviet citizenship), the mental hospital, or the labor camp. Anti-Soviet political behavior, in particular, being outspoken in opposition to the authorities, demonstrating for reform, writing books critical of the USSR were defined in some persons as being simultaneously a criminal act (e.g., violation of Articles 70 or 190-1), a symptom (e.g., "delusion of reformism"), and a diagnosis (e.g., "sluggish schizophrenia").