* AlternativeCharacterInterpretation: the groups of Mesoamerica in general worshipped more or less the same gods but giving them their own spin. For instance, the Chichimec worshipped Tlazolteotl (to the Aztecs a very complex sexual goddess related to sin and forgiveness) as Itzpapálotl, a female warrior goddess. This also explains why there are several sun gods (Tonatiuh and Huitzilopochtli, as even Tezcatlipoca sometimes), several moon gods (Nanahuatzin and Coyolhauxqui) and an unspecified number of deities for the Morning Star (Tlahuizcanpantecuhtli --now that's a mouthful, Xolotl and Quetzalcoatl). Some belive that the most complex figures, like Tezcatlipoca and Xipe Totec come from Toltec culture, whereas other gods such as Huitzilopochtli are the tribal gods from the Aztec's past in Aztlan.
* GermansLoveDavidHasselhoff: The ruling Mexica of Tenochtitlan considered Huitzilopochtli their patron.
* MagnificentBastard: Tezcatlipoca, in spades.
* NeverLiveItDown: The whole mythology tends to be overshadowed by the sacrifices.
* ValuesDissonance: Oh hells yes. None of the gods are really "good" or "evil," and while people from most other cultures are horrified at the vast number of bloody sacrifices the religion entailed, they were seen as absolutely necessary to the practitioners. For instance, the reason for the child sacrifices to Tlaloc? To make sure there'd be rain. Ripping out hearts? Make sure the sun keeps moving across the sky. People being flayed alive? Otherwise the corn won't grow and everyone will starve.
** Why is it so horrific when looked through modern eyes? The babies (YES, BABIES) sacrificed to Tlaloc to insure rain, had to asphyxiate but not drown, and they had to be crying when put in the water, so they blocked their nose and mouth with liquid rubber and slapped them around, then threw them into a pool. The hearts were indeed extracted with the sacrificial "victim" (it was considered an honor to feed the gods) still alive and through what was basically an open heart surgery performed with obsidian blades. The only one that is believed to not be celebrated as such is Xipe Totec's sacrifice; to wit: the offering was either a young virgin boy or girl, who had to be volunteered, who was offered a couple of days of unrestricted abandon regarding food and sex, meaning they had to have sex with as many partners as possible whether they wanted or not. They were then killed and decapitated (or killed by decapitation, but only because it was easier to do the following) and then their entire skin was removed to manufacture a "costume" which was then worn by a priest who proceeded to dance around for days until the skin dried and rotted; symbolizing how the seeds are planted, grow, give fruit and then dry throughout the season. Xipe Totec was HARDCORE.
** Then again, the extremity of these sacrifices has been debated. While there are sacrificial victim remains, isotope testing has shown that cannibalism (one of the main components of these supposed rituals) was rare, so the extreme gruesomeness and cruelty might have been fabricated. Considering the few remaining sources on Aztec culture are highly biased one way or the other...