The Water Lily Jaguar

In the middle of this rollout image is the Water Lily Jaguar. It is on a witz (a living mountain) in between a wahy on the left and Chaak on the right. (There's also a serpent that is coming out of the witz.) The vessel was made between 600s AD and 700s AD, either in Mexico or Guatemala. From the Metropolitan Museum of Art. 

Known today as the Water Lily Jaguar, this underworld (or Xibalbá) god was one of the more major ones the ancient Maya worshiped. It was associated with royalty and libation (pouring liquid as a sacrifice.) The Water Lily Jaguar is still a puzzle for archaeologists, and there are different theories about what the ancient Maya believed about it.

Appearance

This vessel was made between the 600s AD to the
700s AD, in Guatemala. It's style is the Chamá style.
From the Metropolitan Museum of Art.

The Water Lily Jaguar looks like a jaguar that has water lilies on it or next to it and a collar of eyeballs, which could mean the god was connected to sacrifice.

As for the water lilies' placement, sometimes they're on the god, sometimes there's just one flower on its head (and its ears are water lily leaves,) and sometimes they're around it. (One description -- in a paper by J. Andrew McDonald and Brian Stross -- also says that you can find images of the god with a water lily "blade" is on its head, instead of a water lily flower.)

When the flowers are around or all over the Water Lily Jaguar, there are also symbols for Venus, but not just any Venus symbols. These were drawn so they look kind of like water lilies.

There's another notable feature of the Water Lily Jaguar: its teeth. The ancient Maya drew supernatural jaguars' teeth two ways. One way was to draw a fang in the middle of the mouth. The other way was to draw them with a tooth shaped like an ik' sign. But not the Water Lily Jaguar -- the ancient Maya drew it with regular canines.

Connection with Royalty
It looks like the ancient Maya believed the Water Lily Jaguar protected royalty. Another theory about this god's connection to royalty says it might have been a god of male lines of royalty. (Speaking of royalty, there's a burial at Tikal called Burial 196 that had a jade figurine of the Water Lily Jaguar  -- it weighs 3.5 pounds!)

Connection with Libation
Images of elites making libations show them with certain features. One feature is that the elites wear water lilies in their hair. The second feature is that they have jaguar spots on their skin.

Other Connections
One theory about the Water Lily Jaguar says that the god may have been connected to the rainy season. (Because water lilies bloom in the rainy season.) Another theory says that it was a god of plants as well as fertility. Meanwhile, the same theory that suggests the Water Lily Jaguar was a god of male lines of royalty also suggests that it was connected to fire.

References:
Google Books: "Mortuary Landscapes of the Classic Maya: Rituals of the Body and Soul"; Andrew K. Scherer; 2015

San Francisco State University: Mark C. Griffin Associate Professor, Department of Anthropology San Francisco State University: "Jaguar Manifestation in Mesoamerica and Peru"; Amandine Dorian Castex; August 2014

Journal of Ethnobiology": "Water Lily and Cosmic Serpent: Equivalent Conduits of the Maya Spirit Realm"; J. Andrew McDonald, Brian Stross; Spring/Summer 2012

Britannica: Libation

The Metropolitan Museum of Art: Vessel, Mythological Scene

The Metropolitan Museum of Art: Vessel, Throne Scene

Image Credit:
The Metropolitan Museum of Art: Vessel, Mythological Scene (Second additional image)

The Metropolitan Museum of Art: Vessel, Throne Scene (Fourth additional image)

The Waterlily Serpent

This vessel (in the collection of LACMA) comes from Guatemala's
southern highlands. It shows different beings,
including what LACMA calls the Waterlily Monster.

There are different supernatural beings in the art created by the Maya civilization. Wahys -- also known as ways -- are one example. Another example is the Waterlily Serpent as archaeologists call it (among other names.) A god, it seems to have connections to very different things, including water.

Appearance
Descriptions of the Waterlily Serpent can differ somewhat. One way of describing it is to say it's a giant, squiggling snake that has a long, droopy nose, has no jaw, has a long projection coming from the upper part of its mouth and has plumes of feathers on its body. As for its eyes, they've been described as scrolled or spiral. (And, sometimes it doesn't have the body of a serpent. The ancient Maya had images of this being with a human body too.)

The being also tends to have been drawn with a headdress of a blooming waterlily and its pad -- fish are drawn biting the hat or both ends of the serpent, depending on the source.

Names
Other than the Waterlily Serpent, you may find sources that call this being the Water Serpent, Waterlily Monster or Imix Monster, among other names. There are also sources use "water lily" instead of "waterlily." But these are modern names -- what did the ancient Maya call it?

One possible translation for the being's name is witz', which may mean something sort of like moving water. David Stuart, a noted ancient Maya expert, wrote once that its name could be Juun Witz’ Naah Kan, or a variation on that possibility.

Powers and Connections
One thing that this being may have been a god of is water. The exact type of water god it was depends on the source. It may have been the god that controlled just the surface of water. Or it was the god of sources of water on/in the ground such as lakes, cenotes, and running water like rivers.

Some other things in nature that it's thought the Waterlily Serpent was connected to was wind as well as caves (thought to be the places from which wind and water came) and the moon.

The Waterlily Serpent also seems to have been a god connected to certain, more specifically human things, including the Haab' and the Long Count as well as elites. It seems to be connected to rituals the ancient Maya did whenever there was a "period ending." (In the Classic Period, there would be rituals for the end of different periods in the Long Count. Which periods were chosen depended on the community.) Finally, this serpent being is thought to be the god of the number 13.

Uses of the Serpent's Image
The Waterlily Serpent's image as something to wear has been found in the Maya civilization's art. For instance, it looks like there were times that people would dress as the Waterlily Serpent to do period ending rituals. (There are also other images of rulers wearing the serpent's head as a headdress.)

But that wasn't the only way that the ancient Maya used the image of the Waterlily Serpent. Scribes used it as a glyph for Haab' (360 days) in their calendar inscriptions -- sometimes they drew it as a sentient form of the Haab'.

And that wasn't the only way that the ancient Maya used the Waterlily Serpent's image in their writing. The head variant glyph for the number 13 is thought to be the Waterlily Serpent's head. (Head variant glyphs are glyphs that look like heads. They are used as part of monument inscriptions, in a section archaeologists call the Initial Series.)

In terms of art, this being was also a popular choice for painting on ceramics. Artists especially preferred to draw it in a type of theme that archaeologists call the Underwater World.

Consideration: Two Different Beings?
The terms Waterlily Serpent and Waterlily Monster might not mean the same being, because they don't look exactly the same -- a theory separates these two terms based on differences in images that have been studied. They might be two aspects of another being. Or, each might be a being in their own right. Another possibility is that the Waterlily Monster is the Waterlily Serpent's head after it has been cut off.

References:
Google Books: "Art and Myth of the Ancient Maya"; Oswaldo Chinchilla Mazariegos; 2017

Mesoweb: The Pari Journal: "In The Realm of the Witz’:Animate Rivers and Rulership among the Classic Maya"; Jeremy D. Coltman; 2015

Google Books: "Obsidian Reflections: Symbolic Dimensions of Obsidian in Mesoamerica"; Marc N. Levine, David M. Carballo (editors); 2014 

University of Missouri-Columbia: Museum of Art and Archaeology: "End of Days: Real and Imagined Maya Worlds"; November 17, 2012 - March 17, 2013

Google Books: "Breaking the Maya Code", Third Edition; Michael D. Coe; 2012

The University of Texas Rio Grande Valley: Journal of Ethnobiology 32(1): 74–107: "Water Lily and Cosmic Serpent: Equivalent Conduits of the Maya Spirit Realm"; J. Andrew McDonald, Brian Stross; 2012

Google Books: "The Ashgate Research Companion to Monsters and the Monstrous"; Asa Simon Mittman with Peter J. Dendle (editors); 2012

Google Books: "The Technology of Maya Civilization: Political Economy and Beyond Lithic Studies"; Zachary X. Hruby, Geoffrey E. Braswell, Oswaldo Chinchilla Mazariegos (editors); 2011

Google Books: "To Be Like Gods: Dance in Ancient Maya Civilization"; Matthew G. Looper; 2009

Maya Decipherment: Ideas on Ancient Maya Writing and Iconography: "Reading the Water Serpent as WITZ'"; David Stuart; April 3, 2007

University of California, Davis: Maya Hieroglyphic Database Project: Glyph Dwellers, Report 16, December 2003: "The 'Manikin' Glyph Compound (T86:700) as a Reference to Headdresses"; Matthew G. Looper

Mesoweb: Mesoweb Articles: "Maya Creator Gods"; Karen Bassie; 2002  

Image Credit:
LACMA: Vessel with Water Lily Serpent and Underworld Imagery