"Angels in the house", perhaps better known as True Ladies.
Elves if they are close to Tolkien's depiction (high elves). His idea behind them was to depict a people not corrupted by the Original Sin.
Subverted by Tolkien with characters such as Maeglin and Feanor (and his sons).
Indeed, nowadays, this trope is subverted more than played straight for elves, due to people playing up their arrogance or pride. There is a reason there exists drow and dark elves in many settings these days that are purely the opposite of this trope. Indeed, that was actually the case in Dungeons & Dragons before the fans started introducing far too many examples of Chaotic Good drows who are subject to My Species Doth Protest Too Much. For a setting that involves this trope and its evil counterpart and plays them straight on several occasions, this is not very surprising.
The Organians, and possibly the Metrons, on the original Star Trek.
For that matter, most of Star Fleet itself is portrayed as something like this (with a few bad seeds), until the existence of Section 31 was revealed (AFTER Gene Roddenbury' s death of course).
Redwall: Mice, otters, hedgehogs, moles, hares, badgers, squirrels. Shrews are generally Chaotic Good (but always chaotic); voles are good but sometimes whiny.
The Tauren and Draenei—both of which seem to be overwhelmingly honorable on a cultural level—have often been accused of being this (orworse). However, both races have at least a few bad seeds (and representation among Equal-Opportunity Evil organizations).
Seems reasonable that the Draenei would be overly pure since most all of the ones that were more susceptible to corruption have already turned into demons. The ones that exist currently are the ones who fled from that.
The eledhel (“elves of light”) in The Riftwar Cycle live in a perfect Hidden Elf Village Utopia with no internal strife. All named eledhel to date have been unfailingly wise, noble and heroic. Notable because in this world, they are the same race as the dark elves (moredhel), who are war-like and hostile, differing only in their mentality and lifestyle. Though it is possible for a moredhel to embrace the eledhel way of thinking and thus Return and become eledhel, the reverse does not happen. Ever. Making this a case of Incorruptible Pure Pureness.
In Stargate SG-1, the Nox definitely qualify, the Asgard usually do, and the Ancients occasionally do (when they're not AlwaysLawfulStupid, at least), depending on which episode in which series you're watching. Well, the Nox might be more Chaotic Good. Or Lawful Neutral.
Also, Paladins are a literal example. Or at least up until the fourth edition, where they were allowed to be any alignment so long as it matched their patron god.
The Devas, Archons and related Lawful Good entities in The Order of the Stick. They even point out that Lawful Stupid is the Stupidest Thing I've Ever Heard. Entities such as them exist in a state of grace that is literally impossible for mortals to reach, meaning they forgive and tolerate mistakes made by Lawful Good characters - even to the point of such characters embracing Chaos in the form of being The Snark Knight or even a Knight in Sour Armor - as long as they are consistently trying to be Lawful Good.
Best part? This is a high quality Real Life Aesop - good people screw up. Doesn't mean we shouldn't stop trying to be as good as we can be.
Vorlons in Babylon 5 turn out to be another subversion as they are just as petty and terrorizing as their opposing species, the Shadows; while Kosh was literally Lawful Good (for certain values of Lawful; he had no qualms about encouraging The Chosen One—all three parts of...him? Her? Them? Anyway, Sinclair, Delenn, and Sheridan—to bend the rules when necessary to maintain long-term order) the Vorlons as a whole turn out to be merely Always Lawful (Ulkesh being definitely Lawful Evil).
The Eternals in Doctor Who were originally intended to be this, although not much is revealed about them in the show and the Expanded Universe depicts them as having their fair share of villains. Some other species, such as Star Whales and Thals, have also only been seen in a positive light so far.
Animorphs: Deconstructed with Pemalites, a highly developed and joyful race that praised life and abhored violence, so much that when Always Chaotic EvilOmnicidalManiacs the Howlers arrived, Pemalites failed to muster any defence and were exterminated.