Randyll Tarly

"On the morning of my eighteenth nameday, my father came to me. "You're almost a man now", he said, "but you're not worthy of my land and title. Tomorrow you're going to take the black, forsake all claim to your inheritance and start north." "If you do not", he said, "then we'll have a hunt... and somewhere in these woods your horse will stumble and you'll be thrown from your saddle to die. Or so I'll tell your mother. Nothing would please me more."

- Samwell Tarly to Jon Snow Randyll Tarly is an unseen character in Game of Thrones. He has only been mentioned in dialogue. He is the Lord of Horn Hill and the head of House Tarly. He forced his son Samwell Tarly to join the Night's Watch under the threat of death.

Background
Randyll Tarly is the Lord of Horn Hill and the head of House Tarly, a vassal family of House Tyrell of Highgarden. He is a fierce, ruthless warrior and a highly effective general. He is the father of Samwell Tarly and a younger son, Dickon, as well as several daughters.

Season 1
Furious with his elder son and heir Samwell's "womanly" interest in poetry and singing and disdain for martial valor and combat, Randyll ordered Sam to take the black and join the Night's Watch. If not, he'd be found dead one day in a hunting accident. Sam did as he was bid and left Horn Hill for the Wall.

Season 2
Davos Seaworth mentions to Stannis Baratheon that Randyll Tarly is amongst the many lords that have declared for Renly Baratheon.

Season 3
Samwell mentions his father in name when explaining the concept of family names to Gilly. When she points out that Randyll is a handsome name, he asks her to please not give it to her newborn son.

In the books
In the A Song of Ice and Fire novels, Lord Randyll Tarly is considered one of the best battlefield commanders in the Seven Kingdoms, a general able to read the ground, weather conditions, and how a battle is progressing with impressive accuracy. During Robert's Rebellion he inflicted Robert's only defeat, routing his forces at the Battle of Ashford. During the later stages of the rebellion he helped Lord Mace Tyrell besiege Storm's End, and bent the knee after the death of King Aerys II Targaryen. He wields the Valyrian steel sword Heartsbane in battle and is said to be utterly merciless to his foes. Although a ruthless and stern man, he is not outright sadistic, often dispensing strict justice that is nonetheless within the bounds of the law.