Savanti Romero is a Demon Character in the Ninja Turtles TV Series. Satan has made his appearance in the Teenage Mutant Ninja Turtles universe.

Satan has made his appearance in the Teenage Mutant Ninja Turtles universe.

The character Savanti Romero represents a demon. According to TurtlePedia, this character looks like a demon. Here is their description of him:

(Savanti Romero. Click for source.)

"The appearance of Savanti Romero very much resembles a demon. ... on his head there are goat's horns curved backwards. He has hooves instead of legs; he also has a long, massive tail. His skin is yellow and his eyes are red. Two large, sharp fangs grow out of his jaw." [End quote] ("Savanti Romero")

According to TurtlePedia, this demon character is a villain that the Ninja Turtles have to face in some of the episodes from the 2012 TV series. (This is a children's TV show, by the way.) This character wanted to takeover New York and turn people there into "monsters." But, the Ninja Turtles were able to defeat him. 

FOOT MYSTICS - TMNT - NINJA TURTLES - THE OCCULT AGENDA OF THE NINJA TURTLES EXPOSED

(Foot Mystics from TMNT. Click for source.)

FOOT MYSTICS - TMNT -  NINJA TURTLES - THE OCCULT AGENDA OF THE NINJA TURTLES EXPOSED

A number of strange characters appear in the Teenage Mutant Ninja Turtles episodes and comic books. Coming from the notorious Foot Clan, a ninja-like enemy organization that is opposed to the Ninja Turtles, the Foot Mystics use magic power to fight the Turtles and their sensei, a mutant rat named Splinter.

According to TurtlePedia, a website dedicated to the Ninja Turtles franchise, the Foot Mystics can fight on an "astral plane." In the the TMNT animated episode titled "Bad Day," the Foot Mystics use "black magic" to attack the Ninja Turtles on an "astral plane." ("Foot Mystics")