Points of Light
I love the 4e default setting. There is just enough lore to wet the whistle, but not so much as to require reading 3 source books and 47 different novels to sound competent. I appreciate the theme of a few "points of light" struggling against the darkness.
One of the few places to get lore is the Nerathi Legends articles, a short series published in dragon magazine before the release of the Conquest of Nerath board game. Which I am now sorely tempted to buy.
One of the articles (Dragon 403) focused on the realm of the Gorgon King, a small fiefdom of fell giants that have allied themselves with the undead armies of Karkoth. A few hundred of these giants remain, their power since long waned, however they still maintain dominion over their lands.
Monster Concept
The 4e stat block provided a monster that had crowd control abilities and that sparked some interest with me. With the exception of the storm giant, the giants in 5e were... boring. Sure some had armor, and some had different weapons, but the only two actions generally available were "hit it with a melee weapon" or "throw a rock at it".
To be fair, that is what giants do, but I want something more. Enter the fell giant. This giant has a slightly higher AC than normal (for a giant) and plenty of hit points, it should really shine in its crowd control abilities. The throwing chains help the giant tie up loose ends (e.g. wizards) and force them to make strength saving throws. The mace sweep legendary action allows the giant to hit, and potentially knock back all heroes that are gang tackling the monster. Iron mace and shield bash can then be used to focus on a single unlucky target.
The 4e stat block had a darkness spell as a minor action, but I removed it for the sake of simplicity. Feel free to add it back if you think it provides a worthwhile advantage.
Fell giants are never found alone, but are often in the company of orcs, ogres, and other minions. They have no qualm sacrificing their own for a petty advantage.
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