Aspis

"Aspis" (ἀσπίς) is the generic term for the word shield. The aspis carried by Greek infantry (hoplites) of various periods is often referred to as a hoplon (ὅπλον).

According to Diodorus Siculus:

"... and the infantry who had formerly been called "hoplites" because of their heavy shield (hoplon), then had their name changed to "peltasts" from the pelta they carried."

- Diodorus Siculus. The Library, 15.44.3.

Construction
A hoplon shield was a deeply dished shield made of wood. Some shields had a thin sheet of bronze on the outer face, often just around the rim. In some periods, the convention was to decorate the aspis; in others, it was usually left plain. Probably the most famous aspis decoration is that of Sparta: a capital lambda (Λ). From the late 5th century BC, Athenian hoplites commonly used the Little Owl, while the shields of Theban hoplites were sometimes decorated with a sphinx, or the club of Heracles.