Circular Time (audio anthology)

 was a 2007 Big Finish anthological audio release featuring the fifth Doctor and Nyssa. It was the company's first attempt at audio anthology in the main monthly range. Its critical and popular success paved the way for the release's then-unique format to be repeated annually.

The release contained four separate short stories, including:
 * Spring by Mike Maddox from a story by Paul Cornell
 * Summer by Mike Maddox from an idea by Paul Cornell
 * Autumn by Paul Cornell
 * Winter by Paul Cornell

The theme of the compilation, as suggested by the title, was the passage of time — specifically the time of the relationship between Nyssa and the Doctor. A story was taken from each of the major periods of their relationship's life — spring, summer, autumn and winter — to indicate how it matured. Each story was also of a different genre — adventure with aliens on a distant planet, celebrity historical, character piece, and high-concept fanwank. Despite the presence of a cohesive theme, however, the stories shared no narrative continuity at all.