The Creature from the Black Lagoon. Calling it now.
I believe this teaser hints towards The Creature from the Black Lagoon and I am going to, attempt, to detail why.
TLDR- It boils down to more or less this clip. Focus on how the water looks overall and what shapes the actress takes at the 2 minute mark then compare that to the teaser above.
Long details- I need to explain the teaser itself and my thinking beforehand.
First I am assuming the 4th teaser is using the same guidelines as the 3rd teaser who hinted towards Ghostface. In the 3rd teaser the font used for the 3, it being made of blood, and the background all was hints. The font looked like it was made by a knife and roughly looked like a Scream 3 poster. The 3 being made of blood supported it being made by a knife. And the background also looked like a form of white plastic. The other 3rd year images shown the same background and had other Killers in a black/white contrast, but looked somewhat like a negative.
That all pointed towards Ghostface and some here called it. They was right! Now let me put that line of thinking into the 4th teaser.
Before getting into it though I have to point out the skull within the teaser. I am choosing to 90% ignore it. That skull has unofficially been said to be part of the DbD's tally mark logo. I am assuming it has next to nothing to do with the teaser itself and is a red herring added in as a decoy. That teaser is in fact the 2ND teaser! When the teaser was first shown, that skull was missing. So I choose to ignore the skull as of now.
Starting out, the font used. That 4's font at first drove me insane. Spent far too long finding another text that matched it ending up with nothing at all. Then about an hour+ ago I noticed something else that looked like that font. A pair of human legs. In the clip above at the 2 minute mark you will see the actress's legs form a rough shape of the teaser's 4! it is backwards and upside down, but a pair of human legs is 100% able to make the font used in the 4th teaser. The clip also can explain why the 4 stretches all the way down below the image. At the 2:26 mark, the Creature wants to grab her by the leg and drag her down with it. All the way to the bottom.
This clip in my opinion proves that The Creature from the Black Lagoon fits the 4's font and why it oddly goes so far down.
Next is the gold used to make the 4 and spread over the background. Simple enough. TCftBL is from the GOLDEN AGE of classic horror films! Maybe this is a bit too simple of thinking, but it fits the gold used in the teaser and the teasers description referring it to be a "classic license". Not much else to note here in truth.
Lastly, the blackness in the background. I think it is water. At first I thought it was oil due to the skull ozzing black liquid. But after ignoring the skull and comparing to TCftBL, I noticed what shapes the gold in the background took. The gold are varying sizes and shapes of circles in and out of focus. In the clip above you will see that those gold circles look like air bubbles in water! Air bubbles in water look very much like circles of varying sizes/shapes that are in and out of focus to the camera.
Takes a bit of imagination, but the background looking like water makes TCftBL fit this part of the hint as well!
The Creature from the Black Lagoon fits all 3 parts of the teaser and it fits in being a horror classic. The odd font and shape of the 4, the background's colors/textures, and the gold throughout it. Granted this is my interpretation of those hints and there can be MANY ways to interpret a teaser made to be as vague as possible, so this could very well be wrong. But The Creature from the Black Lagoon is the first and ONLY horror movie I have found to come close to fitting everything. And it doesn't just come close, it is a near perfect fit!