The evil being known as Satan or the devil appears very rarely in the Old Testament, but several times in the New.
In spite of his being pictured with horns and a pitchfork, the Bible says nothing whatever about his looks. (Since Satan is evil, artists naturally portray him as ugly.)
Satan and the devils/demons who serve him are depicted as harmful to mankind, tempting us to do evil things and to reject God. The Bible’s last book, Revelation, claims that Satan and his followers will be annihilated at the end of time.
For the present, Satan and the devils can lead people astray—but not unless the people are willing. Comedian Flip Wilson’s old line, “The devil made me do it,” doesn’t square with the Bible.
In the Bible, Satan doesn’t make anyone do anything. Human beings are responsible for their own sins. The devil may tempt people, but people themselves choose to do wrong.
See 209 (angles); 231 (sin).