Dungeons & Dragons, despite having a diverse array of demons and devils to fill the ranks of its evil extraplanar monsters list, has always struggled to make meaningful entries into its list for the opposing team. Perhaps in no small part because of the game's reputation as a refuge for murderhobos? Regardless, to fill the obligatory slot for Neutral Good angels, D&D has traditionally relied upon the Guardinals, a race of benevolent outsiders who just so happen to appear as a melding of man and beast, usually making use of some positive symbolism related to the animal.
Needless to say, Guardinals get a lot of mockery as being, essentially, "furry angels". Making matters worse, D&D artwork for Guardinals traditionally goes in the direction of... well, let's be honest: fucking ugly. If they had to make furry angels, they might have been better off getting actual furries to do the artwork; at least they might have looked somewhat decent.
Guardinals first appeared in the Blood Wars card game way back in 1995, and then made the jump over to the Planescape Monstrous Compendium Appendix II in the same year. They went on to be further detailed in 1999's "Warriors of Heaven". After that, they slowly migrated over to 3rd edition, scattered across several sourcebooks; the Monster Manual 1 and 2, Manual of the Planes, and Book of Exalted Deeds.
The Guardinals are ruled by a group of Patrons - basically epic level demigod members of their race - most known for their brodom with each other, to the point it's implied they're basically an epic tier Good-aligned adventuring party.
Bird-based avian angels, the avorals hold the honor of being both the first guardianal to make the transition to 3rd edition and the one to make the most appearances in 3e in general (Monster Manual 3e and 3.5, Savage Species, Planar Handbook), the only one to receive attention as a player race, and for going through the most Patrons between sourcebooks - from Duke Windheir in the Blood Wars card game to Zvestra in the Warriors of Heaven splatbook to Duchess Sathia in the Book of Exalted Deeds. Avorals make up the scouts of the guardinal forces, using their flight and keen eyesight. They are perhaps best known for being one of the most fucking ugly guardinals of all.
Sathia the Sky Duchess is a CR 26 celestial best known for serving as a patron & muse to painters and sculpters, with a keen eye for artwork.
The satyr-like cervidals are said to make up the bulk of the guardinal "armies", being the closest things they have to professional soldiers. Despite this, they didn't make it into 3rd edition until the Monster Manual 2.
Manath, the Horned Duke, is the second Cervidal Patron to be named in Planescape lore thus far, having taken over from Lord Rhanok (who had the job in AD&D and his own card). The in-universe newest member of the team, he's only CR 20 and feels he has much to learn about his new role, though if he's intimidated at the prospect, he certainly doesn't act it. He's certainly nothing like his curmudgeonly predecessor, which his partners appreciate.
One of the last races to make the edition jump, not appearing until the Book of Exalted Deeds, the equinals are big, good-natured boisterous bruisers who like testing their strength and bashing evil-doers upside the head. They had to wait until the Book of Exalted Deeds to get an appearance in 3rd edition.
As with the Cervidals, their original Patron was lost with the edition change, Lord Hwhyn being replaced by Vhara, the Duchess of the Fields; a 15ft tall CR 24 female equinal who adores flowers (especially gifted bouquets) and hides a generous, emotional nature behind a facade of being aloof and somewhat domineering. Despite this, she's a skillful brawler who can easily tear through small armies of evil humanoids with her bare hands. Hooves. Whatever.
Essentially a race of leonic paladins, leonals are the unofficial leaders of all guardinals, and so their Prince, Talisid the Celestial Lion, has been in charge of them all since he first appeared in Blood Wars. In fact, he's so prominent and powerful - CR 30! - that the band of Guardinal Patrons are officially known as "Talisid and the Five Companions".
Leonals first appeared in the Manual of Planes for 3e, but were reprinted alongside their avoral buddies in the 3.5 Monster Manual.
Angelic wolf-people who constantly hunt down evil. Like the cervidals, despite their commonness amongst the Upper Planes, they didn't appear until the Monster Manual II.
Their Patron, Duke Lucan, was replaced by Kharash the Stalker in 3.5, a CR 22 monster who's essentially a good-aligned assassin/ranger multiclassed character.
A race newly added to the guardinal ranks in the Book of Exalted Deeds, their newcomer status is lampshaded by noting that "The Companions" have never had any Musteval Patrons in their ranks, but they're sure that'll change soon. The smallest of all guardinals at only 2ft tall, these humanoid ferrets are essentially an entire race of golden-hearted rogues.
Bearlike guardinals whose benevolent wisdom leads to them serving as the scholars, philosophers and record-keepers of Elysium in general and the guardinals in particular. They are still 8ft tall bear-people and more than capable of slapping you upside the head if you're an evil prick, however.
Originally lead by Duchess Callisto, she was replaced in the Book of Exalted Deeds - the race's first reappearance in 3rd edition - by Bharrai, the Great Bear. An 18 foot tall, near max-level wizard with god-like intelligence and a bevvy of other powers that make her Challenge Rating 28.
Because Pathfinder never met a D&D 3e element it couldn't try to rip off, it eventually created its own race of Neutral Good celestial furries, and called them Agathions. Credit where it's due, at least they look better than the Guardinals did.