What is the name given to creatures that push the boundaries of biological tolerance?

Creatures that push the boundaries of biological tolerance are known as extremophiles. These organisms thrive in extreme conditions, such as extreme temperatures, acidity, salinity, or pressure, which would be inhospitable to most life forms. Examples include thermophiles, which live in high-temperature environments, and halophiles, which thrive in highly saline conditions. Extremophiles provide valuable insights into the limits of life and the potential for life in extreme environments beyond Earth.