From Beatles hiding behind false names to stars dropping in on their friends' sessions without credit, these famous songs contain some amazing musical guest appearances.

The 1980s practically perfected the enormous romantic ballad: swelling synthesizers, dramatic vocals, and choruses built for slow dancing. But listen past the glossy production and some supposedly swoon-worthy favorites become remarkably uncomfortable. These songs deal with obsession, affairs, jealousy, manipulation, broken marriages, and relationships already falling apart. A few were so routinely misunderstood that their own writers eventually had to explain what listeners had missed.

Turn on a radio in 1979 and you could bounce from disco to power pop to soft rock without touching the dial. The year produced huge singles, unforgettable choruses, and songs that spent decades surviving on classic-rock stations and oldies playlists. For listeners who were there, some of these tunes barely need an introduction.

Some of rock and pop's most memorable fan favorites weren't as well liked by the musicians who performed them.

Brian Jones was the first in a string of musicians that saw the abrupt end of their lives at the young age of 27. What most people don’t know is that Jones’ demise was—and still is—shrouded in mystery.

The 1980s made these musicians famous, but it did not necessarily contain their most surprising work. Some found entirely new audiences decades later, often in places nobody watching MTV would have predicted.