The Inverted Pentacle
Let's get the misconception out of the way. This is not a pentagram, a pentagram is a star NOT enclosed in a circle. This is a pentacle. A pentacle is a 5 point star with one point aligned upwards. However this has two points aligned upwards making this an inverted pentacle. During the 20th century, Satanists inverted the upright pentacle and adopted it as their own symbol. However, the symbol is most commonly shown with the head of a goat within the pentagram. The inverted pentacle with a goat's head is called the Sigil of Baphomet.
The Swastika
Ancient occult symbol of the sun and the four directions. Revived by Hitler, it represents racism and the "white supremacy" of neo-nazis. Like other occult symbols, it is often placed inside a "circle".
Symbol of Bughuul
This is a new symbol seen in the movie Sinister. Bughuul possessed children and fed off of the bodies of the people the children killed.