Summary
In Halo 1, the Covenant dropships are angular, tuning fork shaped craft with personnel bays along the exterior of each "prong". Although not named by Bungie, these vehicles are sometimes called "Apparitions," "Bandits," or "U-shape" by fans.
Between the extended personnel bays, and energy field fluctuates visibly as it generates the ship's antigravity propulsion (similar in appearance to the energy pulse of the "Gravity Lift" elevators the Covenant use to commute between the ground and the hovering ships). This same gravity-beam is used to ferry Ghosts and light ground vehicles to their destinations. In addition to the pilot, the ship is crewed by a single gunner for the under slung bubble-shaped plasma-gun turret--similar to the Shade but with a higher rate of fire. Each troop bay can hold four fully equipped Covenant warriors, as the ship approaches the ground. According to the book Halo: First Strike, these dropships also have life support for use in vaccuum. Contrary to some people's beliefs, they do not have a Slipspace drive, in First Strike, it was dumped out of a ship already in Slipspace, with ample modifications and reinforcements. It cannot travel into the slipstream of its own accord. Apparently, in Halo 2, the Covenant replaced this dropship with the Phantom.