Do we know what Satan looks like? Is there some way we can identify him by his appearance?

No Horns, Red Suit, Or Pitchfork

During the middle ages, people would put on plays where biblical characters were portrayed. When the character of Satan came on stage, he was portrayed as an ugly individual with a red outfit, a tail, horns, and holding a pitchfork. Today, most people immediately think of this description when someone speaks about the Devil. However, this is not how the Bible describes this personage.

No Physical Form

Because Satan is a spirit-being, he has no physical form. The Bible says that angels do not have any physical substance.

Are they not all ministering spirits, sent out to render service for the sake of those who will inherit salvation? (Hbr 1:14).

Though evil angels do not minister to God's people, they still are spirits.

Angel of Light

When he does appear, the Devil appears as an angel of light.

And no marvel; for even Satan fashions himself into an angel of light (2Cr 11:14).

Because Satan is the master deceiver, coming as an angel of light, he appears as a beautiful, tempting, creature—not something ugly or repulsive.

Summary

Contrary to the popular view of the Devil, he is not an ugly creature. Since he is a spirit-being, he has no physical form. When he does appear, it is as a beautiful creature, an angel of light.