I was wondering if heroic monsters were a modern trope, or if there were stories or epics where the heroes were part something monsterous. Obviously, this doesn't include the child of human-like gods such as Zeus or Poseiden, I mean child of a dragon, or child of an ogre or monster.
There is a word that appears in the poem, Beowulf, "aglæca, æglæca" it is difficult to translate and problematic because it is used both for Grendel (the monster) and Beowulf (the hero). Translators often pause with this term because it clearly didn't mean, simply "wretch, monster, demon, fiend" as the first words that are presented with that term in Klaeber's classic presentation of the Beowulf text. He adds the words "warrior" and "hero" so students can have something to use when it applied to Beowulf. More clearly, the word seems to mean "awesome" as in the sense of having great strength and inspiring awe.
The peculiar thing is that both Grendel and Beowulf's dragon are "aglæca, æglæca." And so is Beowulf. That is not to make the case in some simple fashion that Beowulf is a monster or that the monsters are heroes, but it does point to the fact that in the minds of the Beowulf poet and audience, there was something similar, characteristics that were shared by Beowulf and his opponents.
The same is true, in many ways of Gilgamesh and any of the heroes who depended on sheer strength and courage to oppose the monsters that they defeat. Authors and audience recognized that a hero who is really strong and easily bashes his opponents has yet to be defined. I can kill ants by the dozens, but the real test comes when I confront something that is "æglæca" and I am able to prove that I am "æglæca" as well.
That's not what you're asking, I understand, but it is something to consider. The simple answer is, no. The idea of a heroic monster/dragon, etc., would not be possible. There were heroes who were transformed into monstrous shape and who needed to be transformed back into their human form - but that is also not something you seek.
All that said, we must remember "aglæca, æglæca": heroes of strength were regarded by ancient audiences as being monstrous in some ways. Their strength was terrifying and they were often so strong that they could act in anti-social ways because they were not always aware of their own strength. The monsters who they confront in contests that define strength are their equals, and in that defining balance, we see some amount of respect for the monster who is much like the hero.
It’s not exactly ancient literature, but Journey to the West was written in 16th century China and features a variety of leading non-human characters. The protagonist may be a human monk, but his entourage is comprised of a quadruple-immortal stone demon monkey, a cursed pig demon, a cursed sand demon, and a dragon prince pretending to be a horse. I’d say that monstrous/inhuman heroes are far from a modern concept.