Face enemies in the Seiken Densetsu series consist of demonic heads which float around and generally look evil.

Fiend Face

The Fiend Face in FFA is not similar to the other face enemies in the Seiken Densetsu, but it has the name which would stick through the games. It makes different faces at you as it floats around the room. They can only be harmed by magic or the Silver Sword.

Demon

The Demon in FFA is one of the last enemies faced in the Tower of Mana. They drop the strongest helmet in the game, the Samurai Helm.

In SoM Fiend Heads are classified as Demons.

Fierce Head / Demon Head (J)

Fierce Heads reside in the Palace of Darkness and the Underground City. They summon Grave Bat to fight and will spit at you or ram you. They seem to have a higher chance of dropping a Shadow Zero than most enemies.

Fiend Head / Satan Head (J)

Fiend Heads are found in the Mana Fortress and summon Dark Stalkers to fight alongside them. They can spit at your character and poison them. When they get very angry they will turn red and slam themselves into you as an attack. They drop Vampire Capes and an Axe Orb.

In LoM the Fierce Face is classified as Demonic.

Fierce Face

The Fierce Faces in LoM gained a firey mane and lost the ability to summon. Instead it bites at you and spits fire. As a pet it will prevent other enemies from setting you on fire.

In SwoM Fierce Faces are classified as a Demon.

Fierce Face / Demon Head (J)

The Fierce Faces in SwoM retain the look from LoM. They can attack with a magic resistance weakening sound attack and can also use their Fire Breath with a 25% chance of engulfing you in flames. They have a basic Salamander magic attack which breathes fire in a circle around them.

Mean Mask / Satan Head (J)

Mean Masks are simply stronger versions of Fierce Faces.

Fierce Face / Demon Head (J)

In CoM Fierce Faces lose their Salamander magic attack, but deal additional damage when using the sound attack.

Mean Mask / Satan Head (J)

Mean Masks are simply stronger versions of Fierce Faces.