90 Day Fiancé is an American reality television series on TLC that follows couples who have applied for or received a K-1 visa, which allows foreign fiancés of US citizens to enter the United States with the requirement to marry within 90 days. The series premiered on January 12, 2014, and has aired for 10 seasons.

The series has spawned over twenty spin-offs, including 90 Day Fiancé: Happily Ever After, which tracks past couples after their marriages; 90 Day Fiancé: Before the 90 Days, which features couples who met online but have not yet begun the K-1 visa process; and 90 Day Fiancé: The Other Way, where the American partner relocates to their partner's home country. Collectively, the original series and its spin-offs are referred to by TLC's parent company Warner Bros. Discovery as the "90 Day Fiancé Universe" or simply the "90 Day Universe".