With the announcement of his new archival website, Neil Young is doing what few artists are willing to do — release everything they have ever recorded.

Although the lost and unreleased album is becoming less common with digital releases, it’s still common to hold back material from fans, whether it’s for artistic, financial, legal or a plethora of other reasons. Here are some of the most famous lost recordings, what might have happened to them and how they could have impacted music.

Smile – The Beach Boys

Perhaps the most famous unreleased LP of all time, Smile was the planned follow-up to The Beach Boys’ critically acclaimed Pet Sounds. Inspired by the recording process of their smash hit “Good Vibrations,” bandleader Brian Wilson wanted to create a series of vignettes by splicing together hundreds of hours of tape. Dubbed “a teenage symphony to God” by Wilson, Smile even had a planned single titled “Vega-Tables,” where Wilson chewed celery and satirized physical fitness.

Ten months into recording, Smile started to lose support, and Wilson suffered psychological trauma when he revisited it months later. In the 1980s, bootlegs of the album emerged, and the record’s clout grew as a pristine example of chamber pop and even an early post-punk album. In 2011, the band released The Smile Sessions, winning a Grammy for Best Historical Album in 2013 and giving fans an idea of what the album may have sounded like.

Songs from the Black Hole – Weezer

After the success of Weezer’s debut album, most fans expected much of the same power pop on their second effort. However, Weezer’s newfound fame caused frontman Rivers Cuomo to reconsider his life’s direction, leading to a desire to write more complex music. Cuomo wrote Songs from the Black Hole as a science fiction rock opera, using synthesizers and pitch-shifted vocals for several characters.

During the writing and recording of these demos, Cuomo took advantage of Weezer’s downtime to get corrective surgery on his leg. During his time in physical therapy, use of painkillers and self-isolation at Harvard brought the musician to a darker place, resulting in the reshaping of Songs from the Black Hole into Pinkerton — an album initially despised by fans.

Untitled – Amy Winehouse

Drawing her image from girl groups of the 1960s, Amy Winehouse’s soul and blues revival appealed to every demographic imaginable. Before her untimely death in 2011, Winehouse planned to record and release her third album the same year to follow the success of 2006’s Back to Black.

Teaming up with producer Mark Ronson, Winehouse recorded jukebox material in a similar style to that of her previous effort. After her death, several recorded songs were “locked up” by Winehouse’s record label, Island Records, and were to never be. Somehow, one song titled “Procrastinate” leaked and found its way to internet fame.

Black Gold – Jimi Hendrix

The most mysterious and buzz-worthy LP on this list, Black Gold is a series of acoustic demos recorded by Jimi Hendrix in 1970. Prior to a performance, Hendrix gave drummer Mitch Mitchell the master tapes to add rhythm sections, but Mitchell forgot about the tapes after Hendrix’s death, leaving them for 22 years to collect dust. Some fans theorized Black Gold was stolen from Hendrix’s apartment and was lost.

When avid Hendrix fan and collector Tony Brown discovered that Mitchell had the tapes, Brown got a chance to listen to and divulge his thoughts on the album, but never released anything. To this day, only a handful of people have heard the demos and many consider it to be the ultimate Hendrix collectible, a supposed fifth album exploring various themes based on rumored track titles Hendrix wrote on the tapes’ box. In 2010, Hendrix’s sister Janie stated that Black Gold would see a release by the end of the decade, but the only song to see the light of day so far is “Suddenly November Morning.”