While not one of the original classes, the humble Ranger was introduced in Advanced Dungeons & Dragons, 1st Edition, back in 1978. Since then, it's had its ups and downs, considered a prime choice in the 4th Edition and less so in the 5th.
Despite its troubles early in 5e, Rangers have become a respectable part of any adventuring party, with one of Dungeons & Dragons' most recognizable names among their conclaves.
6 Honorable Mention: Saarvin
Introduced in Storm King's Thunder, Saarvin is a gold dragonborn who acts as a guide through the Icewind Dale. He owns many magical items including both armor and a bow crafted from white dragon remains. Icewind Dale is a treacherous place, so to have such confidence traversing it is no simple feat, but something stops the "King of Frozenfar" from a spot in the list: he's not a Ranger. At least, not technically.
While a ranger by trade, his class is described as "Scout", which is a Rogue subclass. He also has no listed level, so while his exploits are impressive, it's difficult to place him accurately.
5 Hank
Hank (left) is a strange one, as many Dungeons & Dragons players have likely seen him without noticing. He and one of his companions, Diana (right), are fighting the dragon on the Dragon of Stormwreck Isle cover. More recognizably, he's one of the main characters of the 1983 TV series Dungeons & Dragons, as well as the layer 1996 comic The Grand Tour. In these, he's a 7th-level Ranger with some powerful gear, though he was (probably) killed by Tiamat down the line.
Hank's party racks up plenty of achievements throughout the series, fighting the typical swathe of monsters. Beholders, evil wizards, a Demodragon (half-demon, half-dragon)—and Hitler. Seriously, look it up. The villain tried to aid the Luftwaffe, and they stopped him. Fortunately, Hank and the gang are on to more domestic adventures as cameos in Dungeons & Dragons: Honor Among Thieves. Nice to know he's not dragon food at least.
4 Minsc
Minsc and Boo, his miniature giant space hamster, are "only" 6th level, but they've had their share of travels. A simple man with a simple view of the world, taking "evil" as his quarry instead of anything in particular, and he tackles it with some success. He's considered a hero in Baldur's Gate, fought off Strahd in Barovia, braved Icewind Dale, fought an Oni as his rival, and survived the depths of Avernus.
While he was with others for all of this, he certainly earned those levels. It's a surprise he isn't a higher level, considering how some heroes from older editions did less for more.
3 Ayo Jabe
For those unfamiliar with Critical Role, Ayo Jabe (center left) led a rival adventuring team in "Call of the Netherdeep". By the end of the campaign, she sits at CR 8, which converts to about 11th or 12th level. She wields a harpoon made from a rare, corrupting metal known as "ruidium", as well as a longbow and some Ranger spells. The extent of her achievements are up to interpretation, as she exists only in the "Call of the Netherdeep" adventure, but 12th level is nothing to scoff at.
The events of Critical Role are considered canon in Forgotten Realms, as is Exandria as a whole. While it may not have been necessary, it's certainly appreciated. Maybe more fan content will be considered canon in the future, however unlikely. Given the release of the recent movie, future content might stay within the Forgotten Realms for now.
2 Ren o' the Blade
Compared to newer editions, Ren's (right) story is a simple one. He was a thief for a time, stealing a set of powerful magic items known as "ioun stones", and escaping with those for a while. After befriending a wizard and cleric, they set off to rescue a pair of druids from Bane, one of Faerûn's most powerful deities. After that, he married a druid, helped to recover a holy relic, the Hammer of Tyr, and died at 15th level. Typical high fantasy stuff.
His adventures were recorded in the 1998 game "Pool of Radiance". While not much in itself, it paved the way for countless other Dungeons & Dragons games for decades to come, and for fantasy games as a whole. While Ren only existed in the 2nd Edition, his impact is felt even today. Without him, fans wouldn't have Baldur's Gate 3 – when it leaves Early Access.
1 Drizzt Do'Urden
16th level, a household name among fantasy fans, and the star of games, comics, and well over 50 published stories, Drizzt Do'Urden is perhaps the best-known character in Dungeons & Dragons. At least, one that isn't in other franchises, like Tiamat. While he's no god, he's also one of the most powerful, able to enter a beast-like state known as the "Hunter", as well as being a skilled Ranger. He also boasts the usual abilities of the Drow, being able to cast Darkness and Faerie Fire innately, and he has a suite of powerful magical weapons.
To list all of Drizzt's exploits – or even his equipment – would be an article in itself, especially since Drizzt's adventures are still ongoing. Lolth's Warrior, the next story in the series, will be released on August 15, 2023. Readers are encouraged to uncover the adventures of Drizzt themselves through R. A. Salvatore's work. The Dark Elf Trilogy is the best place to start.