From Destinypedia, the Destiny wiki
The Hawk is a troop carrier VTOL (Vertical Take-Off and Landing) aircraft that is used by the Last City. It is typically seen making cargo deliveries at the Tower. Hawks are mentioned carrying Guardian reinforcements during The Plaguelands mission by Shiro-4.
During the Red War, it was used as an attack fighter against Red Legion forces; during Homecoming Amanda Holliday used one to drop off The Guardian on The Immortal. Dead Orbit has their own fleet of heavily armed Hawks. They can be seen periodically visiting the Tower Ramparts' Hangar, in the area adjacent to the faction's designated area below the Future War Cult space.
Some Hawks have also been modified to serve Guardians as personal ships:
List of appearances