* Massive stars are defined by their mass. A star is considered "massive" if it's significantly larger than our Sun.

* There's no "least massive" massive star. The line between a massive star and a less massive star is blurry. Astronomers generally consider stars 8 times the mass of our Sun and larger to be massive stars.

So, there's no single star that's the "least massive" massive star. The smallest star that would be considered massive is one that's slightly larger than 8 times the mass of our Sun.