Sheikah Symbol

The Sheikah Symbol is a is a recurring symbol in The Legend of Zelda Series. It is used to represent the Sheikah tribe but has been seen used in many other places. The symbol resembles a human eye, with three triangles above it (as if to imitate eyelashes and/or symbolize the pieces of the Triforce) and a large tear drop running down from the eye. The red tint in which the symbol can be found symbolizes the Sheikah's eye color. After Ocarina of Time, this eye design have made a few appearances throughout the later installments.

The Legend of Zelda: A Link to the Past
A symbol much like the Sheikah Symbol appears in this game. It is seen in Hyrule Castle and on the robes of Agahnim.

The Legend of Zelda: Ocarina of Time
The Symbol appears largely through out this game on walls and clothing. It is seen a lot throughout the Shadow Temple. Many items also contain this symbol such as the Lens of Truth and the Mask of Truth. The symbol also appears on the various Gossip Stones found throughout Hyrule.

The Legend of Zelda: Majora's Mask
The Sheikah make no appearances in this game but the symbol is still used for Gossip Stones and items found in Termina.

The Legend of Zelda: The Wind Waker
The Sheikah Symbol appears in the room where the Master Sword rests along with a picture of Impa. What could be a variation of the Sheikah Symbol also appears in the Forsaken Fortress near Ganondorf's chambers. A variation of the Gossip Stone also appears in this game but unlike other games it does not bare the Sheikah Symbol.

The Legend of Zelda: Twilight Princess
In this game the Sheikah are extinct but the Symbol can still be seen on Howling Stones. Link also receives an item called the Wooden Statue from Impaz, a character theorized to be a descendent of the Sheikah. Strangly the Symbol also appears in the Twilight Realm both on the Fused Shadow and on Zant's Throne.

In the Manga
In the Ocarina of Time Manga the character Sheik explains that the symbol was, in past times, represented as a single eye with no tear. This was changed upon some sort of betrayal by the Royal Family of Hyrule that entailed to the banishment of the Sheikah from Hyrule. In allusion to what occurred, the large tear was added to the symbol.