Which mission first returned samples from a comet?

Stardust was the first mission to return samples from a comet.

NASA launched Stardust in 1999 to collect dust from the coma of comet Wild 2. On 2 January 2004, the spacecraft passed through the comet’s surrounding dust cloud and captured particles in an aerogel collector. The return capsule landed in Utah on 15 January 2006.

Scientists found cometary dust containing minerals formed near the young Sun as well as material associated with colder regions. The results showed that the early Solar System mixed materials across very different temperature zones.

Stardust also collected interstellar dust during its journey, although its major headline achievement was the comet sample return. Rosetta later became the first spacecraft to orbit a comet, while Giotto was the first to image a comet nucleus closely. Those were separate milestones from Stardust’s return mission.