Lou Reed has died at the age of 71. No cause of death has been reported, but the Velvet Underground leader and legendary solo artist underwent a liver transplant in May.

Rolling Stone is reporting that Reed passed away earlier today. He spent more than 50 years making music, first with the influential Velvet Underground in the mid '60s and then as a solo artist, starting in the early '70s with a string of terrific records.

His career has been marked with milestones and several landmark records, including the Velvet Underground's first four albums and '70s solo classics like 'Transformer' and 'Berlin.'

In May, Reed had liver transplant surgery. A month later, it was reported that he was "up and strong" following the procedure. He even sat down for an interview with The Guardian, in which he was his typically biting self, firing shots at the NSA's then-recent spying allegations.

Reed was one of rock's true pioneers. Even though the Velvet Underground didn't sell too many records during their brief lifetime, they became one of the most influential groups of the '70s and '80s, as punk and New Wave bands began adapting their art-noise sound. Reed used his solo career to explore similar music.

His most recent album was the much-maligned 2011 collaboration with Metallica, 'Lulu.' But even that record offered an eye-opening glimpse into Reed's unwavering creative spirit, which he carried with him until the end. He will be missed.