Gargoyle (Doom Eternal)

The gargoyle (called the "harpy demon" or "flying demon" by fans before the Google Stadia footage was released on March 19, 2019) is a new monster introduced in Doom Eternal. Little of it was seen in the game play footage, but what is known is that it can flutter in the air and then land for terrestrial combat. It appears as a small, frail humanoid with bat-like wings, -shaped arms, and -like legs. Shooting it in air instantly stuns it. It also appears to spit acid as a ranged attack.

QuakeCon reveal
The gargoyle was first featured in the QuakeCon 2018 game play reveal. Several instances of the monster are encountered in the city in particular, but they are all eliminated at a distance without being able to effectively attack.

Google Stadia footage
In the Google Stadia game play footage, it can be seen shooting yellow fireballs at the player, and, after it is killed, a codex entry message appears with the confirmed name "Gargoyle".

Trivia

 * A flying demon with a similar nature called the "imp" was originally detailed in the Doom Bible by Tom Hall during Doom's initial development, before the name of imp was reassigned to what was then known as the "demon trooper." It is presently unconfirmed whether or not this detail has had an influence on this new monster design.
 * Winged demons are also seen invading the city in a concept storyboard for Doom 4 1.0. It is unknown if the cancelled Doom 4 had any influence on Doom Eternal.
 * This demon could have been inspired by an enemy of the same name from Monolith's 1997 game, Blood. Its coloring is similar to the Blood version.