Hal Jordan, going back to his earliest Silver Age adventures. The next was the JSA's Alan Scott in JSA/JLA crossovers.
Golden Age Alan Scott (Green Lantern introduced in 1940; later went by "Sentinal")
Hal Jordan (Silver Age Green Lantern first introduced in 1959)
Guy Gardner (1st "backup" GL, introduced 1968; later "Warrior"/later a Red Lantern)
John Stewart (backup Green Lantern introduced in 1971; also was a Darkstar)
Kyle Rayner (introduced in 1994 when the GLC was destroyed; later went by "Ion")
Simon Baz (introduced in 2012 during the New 52)
Jessica Cruz (introduced in 2013; originally known as "Power Ring")
Jennifer-Lynn Hayden (initially Jade, daughter of Alan Scott; given GL ring by Kyle Rayner in 1998)
animated Hal Jordan (seen in comic book based on the animated series published in 2011-2013)
New 52 version of Alan Scott (reimagined Alan from the series Earth 2; introduced 2012)
other (please specify who/when in a separate post)
Hal Jordan, going back to his earliest Silver Age adventures. The next was the JSA's Alan Scott in JSA/JLA crossovers.
Doctor Bifrost
"If Roy G. Bivolo had seen some B&W pencil sketches, his whole life would have turned out differently." http://doctorbifrost.blogspot.com/
Kyle Rayner during Morrison's JLA run.
Bought that issue off a Toys R’ Us newsrack way back when and was hooked ever since until DC’s tripling down on Hal being the de facto GL and made me walk away
Kyle in the Joe Kelly JLA.
John was probably the second, since I recall Kelly replaced Kyle with John following the Obsidian Age story.
Hal Jordan in Geoff Johns' Green Lantern: Secret Origin storyline.
Technically Hal Jordan in a cameo of a few panels in some ancient Superman book.
Kyle in Morrison's JLA was the first one I knew as a character. Alan Scott in Geoff's JSA the second.
Kyle in Morrison's JLA. Hal when I started on the GL franchise proper.
It was Hal Jordan, in early 1967, on a Saturday, at Ryan's drugstore.
This would have been very early in my comic book buying career (reading started much earlier, but I had only recently gotten in the habit of buying my own comic books, rather than relying on the kindness of strangers). On that day I bought JUSTICE LEAGUE OF AMERICA 52 (March '67) and probably DETECTIVE COMICS 361 (March '67).
The 'TEC was one of my favourite comic books of all time. The JLA not so much. It was the worst comic to get, if I wanted to read about the Justice League, because it wasn't a Justice League story. I bought the comic book, because Batman and Superman appeared prominently on the cover. And Mrs. Ryan didn't let you read the comic book before you bought it, so I was going just by the cover in choosing to buy it.
I had no idea what a Justice League of America was and by the end of the comic book I was no wiser. I read most of the comic book walking home from the drugstore and the big thing that impressed me was the Green Lantern scene, where Hal charges his ring, saying "In Brightest Day, In Blackest Night, No Evil Shall Escape My Sight. Let Those Who Worship Evil's Might, Beware My Power, Green Lantern's Light."
I read those lines over and over again. I thought that was some of the most stirring poetry I had ever read. And I committed every word to memory--quite happy with myself that I could do that--and for the next week I bothered everyone I met by reciting those lines-- "In Brightest Day, In Blackest Night, No Evil Shall Escape My Sight. Let Those Who Worship Evil's Might, Beware My Power, Green Lantern's Light."--over and over again.
Funnily enough, I never bought a lot of GREEN LANTERN comics after that (not for many years). At that age, I mainly stuck with Batman and Superman. I didn't even buy many JUSTICE LEAGUE comics. I did soon after this get a GL comic at the school bazaar in a kind of grab-bag giveaway--GREEN LANTERN 27 (March '67). A very great comic book--reminded me of THE OUTER LIMITS and TWIGHT ZONE with its two stories.
And I did get a few GL issues new in the months ahead, but I think that Mrs. Ryan probably didn't stock a lot of GL or JLA comic books. And most of my weekly allowance of 25 cents went toward Batman and Superman comics--there wasn't much else I could afford, just the occasional Gold Key comic book (TARZAN and others).
Hal. But the first one I took an interest in collecting and really reading about was Kyle.
It was a John Stewart comic dealing with a corrupting influence from within his ring.
My first GL was Hal via Superfriends, and later from my uncle's massive comics collection. Alan would be my second, also from my uncle's comics collection.
I discovered John (and Kat) a bit later from the last panel on a New Teen Titans book (when the team was defeated by Brother Blood).
Hal Jordan, Green Lantern Rebirth was when I started reading the GL books, and that's where I learned that all of the things I assumed had always been a part of their mythos had been created by Geoff Johns and Ethan van Sciver.