House Forrester was talked about in Dance of Dragons, I believe. They're Glover bannermen.
Lady Sybelle Glover provides scouts from House Forrester to Stannis Baratheon for his march through the wolfswood from Deepwood Motte to Winterfell.
The known Forresters appearing in Game of Thrones - A Telltale Games Series are:
Gregor Forrester, Lord of Ironrath and loyal to House Stark.
Elissa Forrester, Gregor's wife of House Branfield.
Rodrik Forrester, the first-born son and heir of the House, with a prominent military background.
Asher Forrester, the exiled son of the House, who resides in Essos, after he nearly took his House to war.
Mira Forrester, the eldest daughter of the House and a handmaiden to Margaery Tyrell.
Talia Forrester, the second-eldest daughter of the House.
Ethan Forrester, the third-born son of the House and Talia's twin.
Ryon Forrester, the youngest son of the House.
Household
Maester Ortengryn, a trusted advisor to the Lord, who originates from a minor house in the Vale.
Ser Royland Degore, the master-at-arms for the House, who was knighted by King Robert after he played a crucial role in the siege of Pyke that ended Balon Greyjoy’s rebellion. His family was wiped out by Ironborn.
Duncan Tuttle, the Castellan of the House and a good friend of Lord Forrester.
Gared Tuttle, squire to Lord Forrester and nephew to Duncan.
Malcolm Branfeld, brother of Elissa and, with her, the only surviving members of House Branfield.
Historical Forresters
Cedric Forrester, who, with his sons, built Ironrath, the seat of their House.
His triplet sons.
