Olyvar

"I shall like to see you spar with a proper partner Ser."

- Olyvar to Loras Tyrell

Olyvar is a male prostitute and spy working for Petyr Baelish who is first seen in "Kissed by Fire". He is portrayed by Will Tudor.

Season 3
Olyvar poses as Loras Tyrell's squire during a sparring match. He makes flirtatious advances toward Loras and the two later have sex. Olyvar discovers that Loras is due to be married, and relays this information to Littlefinger shortly thereafter. Olyvar implies that noblemen in Loras's position make up the bulk of his clientele.

In the books
In the A Song of Ice and Fire novels, there is no prostitute named Olyvar. The character in the series assumes the role given to Dontos Hollard in the books, that of a spy for Littlefinger who reports the plot to marry Sansa Stark to a Tyrell. Dontos becomes Sansa's friend, and she shares with him the plot to marry her to Willas Tyrell. Dontos reports this back to Littlefinger, who proceeds to inform the Lannisters. Since Dontos was largely cut from the series, the writers needed another way for Littlefinger to find out about the plot, hence Olyvar.

The name appears only in the person of Olyvar Frey, a character completely unrelated to Olyvar or Dontos Hollard. In the series, the name is pronounced identically to the real-world "Oliver".