Thomas Lasky has served in the UNSC for over thirty years, and has been involved in combat since the age of fifteen. Lasky is the child of Colonel Audrey Lasky, an officer in the UNSC, and therefore was sent to the Corbulo Academy of Military Science in late 2525 or early 2526. His schooling was cut short by the Battle of Circinius IV in April 2526, one of the first colonies attacked by the Covenant. After surviving the Battle of Circinius IV, Lasky served various roles in the UNSC throughout the remainder of the Human-Covenant War. Soon after the ending of hostilities with the Covenant at the end of 2552, Lasky was promoted to Commander and served as executive officer of the UNSC Infinity under Captain Andrew Del-Rio. Lasky remained as commander until after the Battle of Requiem in July 2557, when Del-Rio was removed from command and Lasky was promoted to Captain of the Infinity.
As captain of the Infinity, Lasky led the Requiem Campaign in 2558, as well as several conflicts with Jul ‘Mdama’s forces trying to obtain control over the Forerunner Janus Key. After Operation: ATHENA which saw the destruction of the Janus Key, Lasky sent Fireteam Osiris into the Battle of Kamchatka to recover Doctor Catherine Halsey and eliminate Jul ‘Mdama. He then commanded the Infinity during the Raising of the Guardians, which resulted in the Infinity narrowly escaping from Cortana’s attack on Earth. As of late 2558, Lasky remains as captain of the Infinity, which is in hiding from Cortana and her Created.