House Caulfield is a noble house from Westeros.
Samwell Tarly presents some paperwork to Lord Commander Jon Snow consisting of requests to various noble Houses to send new recruits to the Night's Watch. Few Houses can spare any men during the War of the Five Kings so the Watch is left scraping the bottom of the barrel: the requests are mostly to minor lords that Jon says he hasn't even heard of, including Lord Ashford, Lady Caulfield, Lord Smallwood, Lord Mazin, and Lord Wibberley.
- Lady Caulfield, head of the house.
In the books
In the A Song of Ice and Fire novels, there is no mention of any House Caulfield. The episode itself makes a joke about this when Jon Snow remarks that he has "never even heard of these people".
The name - and specifically the fact that it is a Lady Caulfield - is apparently a reference to one of the TV series's producers, Bernadette Caulfield.