Who wrote the 'Foundation' series?

Isaac Asimov wrote the “Foundation” series.

The series began as science-fiction stories and novellas published in “Astounding Science-Fiction” from 1942 to 1950. These stories were collected into the original “Foundation Trilogy”: “Foundation” in 1951, “Foundation and Empire” in 1952, and “Second Foundation” in 1953.

Asimov based the series’ broad historical idea on the rise and fall of civilizations, especially Edward Gibbon’s account of the Roman Empire. Its central concept is psychohistory, a fictional mathematical discipline developed by Hari Seldon to predict the broad behavior of enormous populations and prepare for the Galactic Empire’s collapse.

Asimov later expanded the saga with two sequels and two prequels. Other writers also produced authorized novels after his death, but those later additions do not change the canonical answer to who created and wrote the original series. Ray Bradbury, Robert A. Heinlein, and Arthur C. Clarke were influential science-fiction authors, but they did not write “Foundation.”