John O'Neil
John's family (Agnes Hair O'Neil and their children) traveled to America together in 1864. They are seen together on both the ship roster (The General McClellan) as well as the William Warren overland company records. However, John is not seen with them. It is likely that he hired on as a teamster, but it is not entirely certain when he traveled to Utah or which company he traveled with.
He and his wife had a daughter in December of 1866, which would have put him in the Valley by the 1865 emigration season. Further research is needed.
Note that in some sources the family's surname is spelled "O'Niel."