The bass clarinet is a remarkable instrument. Not only does it have a huge range, both in pitch and dynamics, but it exhibits almost unbelievable nimbleness and agility in the bottom register. It even inspired Adolphe Sax, the inventor of the saxophone, to adopt the upturned bell for his instrument.
It’s probably not too surprising that Hector Berlioz was one of the first composers to use the bass clarinet in an orchestral setting from around 1840 – it must have greatly appealed to both his love of strange sonorities and slightly eccentric demeanour. Wagner and Verdi both loved it too making it a staple of the opera orchestra, and by the 20th century it was all over the place – from Ravel to Mahler, Bernstein to Reich.
By the way, if you like the bass clarinet, you should really check out the contrabass clarinet...