I recently contacted an expert on the life of Billy the Kid who offered what she knew about Tom O'Folliard:
Tom O'Folliard Jr. was born in 1858 in Uvalde, Texas. His parents were Irish immigrants (does anybody know if their names are in the passenger arrival lists?), his father was Tom O'Folliard Sr. and his mother, Sarah Cook; both died of smallpox when he was just a baby, so his uncle (his mother's brother, John Cook) became his guardian. His uncle then married a Miss McKinney which made Tom O'Folliard and Thomas "Kip" Mckinney cousins (Kip was one of the two deputies who was present when Billy the Kid was killed by Sheriff Pat Garrett). After his uncle married, Tom went to live with his grandmother.
Why, how, and when he left and headed to New Mexico isn't known. All we do know is in the spring of 1878, he was in Lincoln, New Mexico and joined up with the Regulators and fought in the Lincoln County War and became Billy the Kid's inseparable pal. He was killed by Pat Garrett and his posse on December 19, 1880 in Fort Sumner and was buried in the old fort military cemetery. He never married or had children.
I would be very interested to know what will happen to all the archive material that the late Robert Folliard accumulated. If Tom (my brother) and I can be of any assistance at all, please do not hesitate to contact me.