The marketing for Legendary's Godzilla: King of the Monsters centered on Godzilla, Rodan, King Ghidorah, and Mothra, but the four classic Toho kaiju third M.U.T.O. The rest have been mentioned by name, but so far have gone unseen. It should be noted that these 17 Titans aren't the only monsters in the MonsterVerse. Kong: Skull Island included quite a few of its own, but only its ruler, Kong, has the physical characteristics to be classified as a Titan.
In the final scene of Godzilla: King of the Monsters, winged creatures can be glimpsed flying in the background in the shot where Behemoth approaches Godzilla. They're so far away that they could easily be mistaken for bats or even birds, but at closer inspection, it's clear that they're identical to the Leafwings from Kong: Skull Island. The Leafwings were bat-like, reptilian creatures that were spotted by the of the Monarch expedition. A large gathering of them were perched on a tree, until Packard (Samuel L. Jackson) shot one of them and caused them to scatter. Later, they grouped together and began picking off the soldiers.
What Are Leafwings?
Godzilla: King of the Monsters director Mike Dougherty confirmed the identity of the flying creatures [via Bloody Disgusting]. Dougherty says he likes the idea that the Leafwings may have escaped from the Hollow Earth after the other Titans emerged from the ground. An alternate explanation is offered in the novelization of King of the Monsters, which states that the Leafwings were captured and placed in captivity on Monarch's Outpost 33 on Skull Island. Apparently, the Leafwings were somehow freed by the conflict caused by King Ghidorah.
Either way, the Leafwings are a neat addition to King of the Monsters, and just one of many Easter eggs hidden throughout the film. Viewers may end up seeing them again in Godzilla vs. Kong, except this time they'll be in their natural habitat.
