Bass has many forms -- electric, upright, synthesized. Whatever its shape, it is a crucial element to popular music.
Most songs don't need good bass lines, but the ones that have them are propelled into greatness. Here are the six best bass lines. Please note that bass parts that parrot guitar parts (i.e. "Day Tripper" or "Sunshine of Your Love") have been intentionally omitted.
6. Queen -- "Another One Bites The Dust"
If you haven't heard "Another One Bites The Dust" in a while, you need to. The production is insane -- backward pianos and cymbals, and some weird noise that sounds like TV static and helicopter blades. It's all anchored by the simplest, deepest bass line possible. Sure, things get flashy for a few bars here and there, but it's those three thumps that line up perfectly with the kick drum that make the track so solid.
5. Michael Jackson -- "Billie Jean"
MJ knew the importance of a good bass line, something he learned as a child (I am foreshadowing) and only forgot around the time of his Dangerous album. None of the songs released under his name hit as hard as "Billie Jean." That spry synth-bass walk is an intravenous injection of low end, a hypnotic get-yo-ass-on-the-floor call to your intestines. Just listen to the way the tune opens up during the "People always told me, be careful what you do" passage, when the line gives way to long notes. It's almost metaphorical for Michael, how the disappearance of the bass line making you realize you had been taking it for granted for so long. Unfortunately, the King of Pop can't just rise from the dead and drop in harder than ever before. Luckily for us, the chorus of "Billie Jean" can.
4. Black Sabbath - "War Pigs"
Sabbath's Paranoid opens with a sludgy waltz that is essentially a solo for bassist Geezer Butler. His work on the first 30 seconds of "War Pigs" is a treatise on rock bass. He lays low when needed but is not afraid of jumping into elongated fills. Butler plays bass like a second guitar; that's not always the best approach, but when it's good, people are still emulating it 40 years later (see: the Sword, Black Mountain).