2MASS J0523-1403 is a brown dwarf companion to a nearby red dwarf star. The object was discovered by the Two Micron All Sky Survey (2MASS) in 2003. Located 40 light-years (12 parsecs) away from Earth in the constellation Orion, it is one of the closest brown dwarfs known.

It has a surface temperature of about 2,200 Kelvin (1,900 °C; 3,400 °F), and a mass about 20 times that of Jupiter, thus putting it right at the boundary between being a brown dwarf or an exoplanet.

The object is of great interest to astronomers because it is relatively bright and close, and thus offers an excellent opportunity to study the properties and evolution of very low-mass stars and brown dwarfs.

It is also surrounded by a thick dusty debris disk rich in silicates, that might be the remains of a planetary system in formation or, more likely, the result of a more recent catastrophic collision.

The age of the 2MASS J0523-1403 system has been estimated to be about 100 million years based on its kinematics.