Fauna & Flora International (FFI) is an international conservation charity and non-governmental organization dedicated to protecting the planet's threatened wildlife and habitats. Founded in 1903, it is the world's oldest international conservation organisation. The logo of the society is the Arabian oryx, after the successful Operation Oryx, a flagship captive breeding and reintroduction project undertaken by the society.

Founded as the Society for the Preservation of the Wild Fauna of the Empire, the society created some of the first game reserves and captive breeding programmes during the 20th century. Having since gone through several name and approach changes, FFI today coordinates conservation programmes in around 40 countries, working through local partnerships and with more focus on capacity building, community-based approaches and marine conservation than its previous iterations. The society's peer-reviewed scientific journal, now known as Oryx, has been publishing conservation science articles since 1904.

Fauna & Flora International is constituted under English law as a company limited by guarantee and is a registered charity with its head office in Cambridge. FFI has sister organisations in the U.S. and Australia, and a subsidiary in Singapore. FFI currently runs conservation programs and activities in around 40 countries in collaboration with local partner organisations, institutions, communities and authorities.

FFI has a long history of royal patronage dating back to Edward, Prince of Wales (later Edward VIII), who became the group's patron in 1928. Queen Elizabeth II was FFI's patron for 68 years after her ascension to the throne until this was delegated to Prince William, Duke of Cambridge in October 2020 to align with his "longstanding work around conservation and support for communities protecting their natural environment for future generations." Princess Laurentien of the Netherlands is FFI's current president. FFI also has a number of high-profile vice-presidents, including David Attenborough, who has been involved with FFI since 1959, Stephen Fry, Charlotte Uhlenbroek, and Lord Browne of Madingley.