Ser Pistus

A few useful FAQs: How did Arya kill her target? Are Targaryens immune to diseases? Who killed all these men in Winterfell (and who killed Little Walder?) What happened to the three missing Freys? Who is Septa Lemore?

There is another possibility, and I like it. After inventing Samwell, GRRM realized the name's similarity to Samwise, and then put in this small homage. Just a little joke, nothing meaningful. I also heard that in the TV series there is a dialogue between Sam and Pip (Pippin, you see) that also contains a LotR homage, but now I cannot recall it.