The first and most famous "failed star" discovered by humanity isn't one brown dwarf, but two! The duo comprising Gliese 229B are so tightly bound they orbit each other in 12 days.

These 'failed stars' orbit so closely it took 29 years to tell they were a pair

Source: space
Source Link: https://www.space.com/brown-dwarf-failed-star-binary-gliese-229b