Given that Cucumber Quest is the basis of my username, I'm glad I have a case of a character from the work potentially qualifying.
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The first Legendary Hero.
What's the Work?
Cucumber Quest is a science fantasy webcomic. In the story, a reluctant boy called Cucumber and his sister, Almond, are sent on a quest to save the world of Dreamside from the Nightmare Knight and Queen Cordelia.
Who is He?
Gherkin is the first Legendary Hero, and is the ancestor of Cucumber and Almond. He is mentioned throughout the story as the only known Legendary Hero, as every successor to him was forgotten.
What has he done?
He was the only legendary hero to defeat the Nightmare Knight and Disaster Masters legitimately, as the Nightmare Knight was still evil and motivated. During this time, both he and his Disaster Masters caused chaos, which included forcing the citizens of Rhythm Ridge to evacuate their home, and reducing Botanica to an uninhabited ruin. This defeat set the Knight on a path to redemption, causing him to assist the other Legendary Heroes by sabotaging them to protect the Dreamsiders, and allowing the previous 98 heroes to defeat him.
What makes him close to Pure Good?
In addition to the previous under What Has He Done:
He defeated Count Legato, a magician who betrayed King Bass and took over and ruled Organetto with an iron fist.
He rescued his sister Peanut many different times.
His actions have caused him to be known throughout Dreamside as a hero who freed various kingdoms.
Gherkin is the most admirable character for the resources he has, having defeated the seemingly unstoppable Nightmare Knight and Disaster Masters when the former didn't intentionally hold back and sabotage the latter.
Only the aforementioned Nightmare Knight, a reality warper, is more admirable than he is, and that is because he saved various people every time he was summoned, something that Gherkin was unable to do, since he was presumably long dead.
While the Nightmare Knight describes him a "brazen child", and he once called the Nightmare Knight "Nightey Knight", there is nothing to indicate that he was overly arrogant toward his enemies.
What prevents Him from being Pure Good?
He is a bit too insufficiently characterized, with his actions only told to us by other characters, such as by an in-universe pamphlet or by characters like the Nightmare Knight. However, actions such as rescuing his sister and defeating Legato may suggest that he was at least somewhat altruistic.
Verdict?
A Yes from me.