Thaddius Riker
From Memory Alpha, the free Star Trek reference
Colonel Thaddius Riker was a soldier in the Union Army during the United States of America Civil War. He was a distant ancestor of Kyle and William T. Riker.
Known to his compatriots as "Old Iron Boots", Colonel Riker was in command of the 102nd New York Infantry during Sherman's March to the Sea on Atlanta.
During the campaign, Colonel Riker was wounded at the Battle of Pine Mountain, Georgia, in late June, 1864. He was carried back from the front line by another soldier who was actually discovered, in 2372, to be a Q.
Without the actions of this Q, there would have been no William T. Riker, which would have allowed the Borg to assimilate the Federation. (VOY: "Death Wish")
[edit] Background
Although there was never a real Colonel Thaddius Riker, much less one who commanded a regiment that participated in the Battle of Pine Mountain, there was a 102nd New York Regiment that did fight in the Atlanta Campaign under Sherman in 1864.
The person in the photograph is actually Major L.R. Stegman of the 102nd New York Regiment, as can be seen on page 289 of F. Miller's The Photographic History of the Civil War, vol. 7 (1911). He was standing next to a Lieutenant Donner from Ohio, although an image of Gerrit Graham as Q was imposed over Donner.
The US insignia for a colonel was a silver embroidery shaped like a stylized eagle, holding olive branches in one claw and arrows in the other, with the eagle's beak facing the side he held his arrows (the so-called "war eagle"). The colonel's insignia was displayed on two epaulet shoulder straps with colored backgrounds. While Thaddius Riker was not seen wearing his uniform insignia, as an infantry colonel, his eagle would have been on a field of medium blue.
