Name: Ian Alastair Robert MacLeod Murray
Born: 1720 (Ian is one year older than Jamie)
Died: March 10, 1778
Home: Lallybroch (or Broch Tuarach)
Parents: Auld John Murray and ??
Siblings: We know he has a married sister, but not her name
Wife: Janet (Jenny) Fraser
Children: James ("Young Jamie"), Margaret Ellen ("Maggie"), Katherine Mary ("Kitty"), Caitlin Maisri (died at birth), Janet and Michael (twins), and Ian ("Young Ian")Ian Murray is Jamie's brother-in-law. He manages Lallybroch.
We know that Ian and Jamie grew up together and were best friends since childhood. They also served together as mercenaries together in France (Virgins novella) near the Spanish border, where Ian lost his right leg to a grapeshot injury that went bad. Jenny nursed him back to health, and she is the one who told him that they would get married.
Ian doesn't show up as an on-screen character until the second half of the first season when Claire and Jamie return to Lallybroch.
Ian is very even tempered and is a good match for Jenny who is very hot-tempered.