The Type 21 frigate, or Amazon-class frigate, was a British Royal Navy general-purpose escort that was designed in the late 1960s, built in the 1970s and served throughout the 1980s into the 1990s.

The Leander-class, or Type 12I (Improved) frigates, comprising twenty-six vessels, was among the most numerous and long-lived classes of frigate in the Royal Navy's modern history. The class was built in three batches between 1959 and 1973. It had an unusually high public profile, due to the popular BBC television drama series Warship. The Leander silhouette became synonymous with the Royal Navy through the 1960s until the 1980s.