There isn't a shortage of weird and wonderful Green Lanterns in mainstream DC continuity, but, as is often the case with comics in general, it's the ones found in alternate universes that are by far the most insane.
DC is familiar with the concept of 'alternate Earths' more than most other publishers, and while they've tried to divest from them on certain, multiverse-shattering occasions (hello, Crisis!), it always finds a way of coming back. And why shouldn't it? DC are renowned for their iconic universe, but also for their own brand of 'Elseworlds' tales that optioned exciting - and sometimes disturbing - twists on classic company staples.
They've done it with Batman, Superman, and practically every DC hero you can think of, including Green Lantern. The GL Corps has seen some colourful characters over the years, but it's away from mainstream continuity that writers and artists have been able to ask some of the most interesting questions about the property and the figures that reside within it.
Ever wondered what would happen if Green Lantern became an evil dictator (again)? Elseworlds has you covered, as it does if you've ever pondered what the character would be like 3000 years from now, if Batman ever wielded the ring on a full-time basis, and even what would've been if Marvel's Stan Lee had a hand in his creation...