Stalfos are an enemy that are living skeletons in Zelda 1.
Stalfos are found within various dungeons across Hyrule. They walk around in a random pattern as they swing their two swords, damaging Link upon contact. In the Second Quest, they have the ability to shoot sword beams similar to Link's. Stalfos can be defeated with any item.
Artwork of a Stalfos that originally appeared in The Legend of Zelda Instruction Booklet
"A skeleton that's got a sword in each hand. Little attacking power."
— The Legend of Zelda Instruction Booklet