Hugh

"Ah, a knight. They strut around like roosters down here. Even the ones who have never seen an arrow coming their way."

- Eddard Stark on Hugh's lack of manners

Hugh, called Ser Hugh of the Vale, is a recurring character in the first season. He is played by guest star Jefferson Hall and debuts in "Cripples, Bastards and Broken Things." Ser Hugh is a freshly made knight. He is killed by a splintered lance while jousting with Ser Gregor Clegane.

Background
Hugh served as Lord Jon Arryn's squire for four years before Jon Arryn's death. After Arryn's death, Hugh was knighted for his loyal service by King Robert Baratheon. When Lady Lysa Arryn returned to the Eyrie with her son, Ser Hugh elected to remain in King's Landing in the King's service.

Season 1
Lord Eddard Stark sends Jory Cassel to quiz Ser Hugh about Jon Arryn's death. Ser Hugh refuses to talk to Jory since he isn't a knight. Ser Hugh takes part in the tournament to celebrate Eddard's arrival and is killed by a splintered lance during a joust with Ser Gregor Clegane.

Lord Commander Barristan Selmy stands the knight's vigil for Ser Hugh overnight. Eddard ponders how Hugh could afford arms and armor so soon after being knighted, leading him to suspect that Hugh was involved in Jon Arryn's death. Varys later agrees that this is the most likely explanation, and that the Lannisters ordered him killed to prevent him talking (Ser Gregor is in the Lannister's service).

In the books
In the A Song of Ice and Fire novels, Ser Hugh is a reasonably effective warrior but is newly-proud and slightly drunk on his achievement of becoming a knight.

Lord Stark met Ser Barristan at a cart transporting Ser Hugh's remains after the silent sisters had dressed him. Ser Barristan explains that he did stand vigil alone, but Ser Hugh apparently has a mother in the Vale and the remains are being send to her. Ser Hugh's armor is new since he had it made especially for the tournament and has not been completely paid for, but Lord Stark will deal with the armorer himself and insists to the silent sister accompanying the cart that Ser Hugh's mother receive his armor since he knows it will mean something to her.

When Grand Maester Pycelle is being accused by Tyrion Lannister of fatally poisoning Jon Arryn, Pycelle denies it while accusing Ser Hugh of doing it and that Varys and Queen Cersei will concur with Pycelle about Ser Hugh's guilt.

Upon being knighted, Ser Hugh's sigil is a blue field bordered in crescent moons.