Ryler Dorant, also known by his alias Needles, was a Human male physician. Serving the Galactic Republic's military, he held the rank of lieutenant within Havoc Squad, an elite unit composed of Republic troopers. Alongside the majority of Havoc Squad, he switched his allegiance to the reconstituted Sith Empire during the Cold War that transpired between the Republic and the Empire.
In the year 3643 BBY, Ryler functioned as Havoc Squad's medic, with a primary focus on the synthesis of combat stimulants. He was stationed on the planet of Ord Mantell during the Separatist War. This conflict was a component of the broader Cold War that was initiated when the returning Sith Empire concluded their invasion. During the Separatist War period, he and the bulk of Havoc Squad chose to defect to the Sith Empire, with the exception of one solitary member.
Ultimately, Needles made his way to Taris and proceeded to weaponize the rakghoul plague. He conducted trials on newly defected Republic soldiers and captives supplied by the Death's Claw pirates operating from Fallenspire Stronghold, aiming to accelerate its effects. The reformed Havoc Squad, under the leadership of the original member who remained loyal, successfully neutralized Needles and halted his experiments. Subsequently, Elara Dorne assumed his role within Havoc Squad.
Dorant's laboratory later became the target of Ki Sazen, a renegade Jedi. She sought his research regarding the rakghoul virus as part of a scheme to raise a rakghoul army using Doctor Nasan Godera's Ultrawave Transmitter, with the objective of seizing control of the planet.