Which star is the brightest in the constellation Leo?

Regulus is recognized as the brightest star in the constellation Leo. It is a blue-white main sequence star located about 79 light-years from Earth. Regulus shines with an apparent magnitude of about 1.35, making it easily visible to the naked eye and prominent in the night sky. It holds a significant position in Leo, as it is often referred to as the "Heart of the Lion." In addition to its brightness, Regulus is part of a binary star system, which contributes to its interesting astrophysical characteristics.

The other stars mentioned, such as Betelgeuse, Arcturus, and Deneb, are indeed bright and significant stars in their own right, but they belong to different constellations. Betelgeuse is part of Orion, Arcturus is in Boötes, and Deneb is located in Cygnus. Therefore, while they are notable stars, they do not compete with Regulus when it comes to brightness within the constellation Leo.