Lieutenant Commander Donna O'Neill, or "D.O.", was a Starfleet officer who served during the historic first mission of the Enterprise under Captain Jonathan Archer. With red hair and a short stature, D.O. served as third watch commander on the Enterprise from late 2152, until at least 2159. (ENT novels: What Price Honor?, Rosetta, The Good That Men Do, Kobayashi Maru, Beneath the Raptor's Wing, To Brave the Storm)

D.O., like Enterprise shipmate Travis Mayweather, was a space boomer, born on a freighter on a long-haul run. She eventually became aware that she wanted more than a freight-haulers life, and found her calling with Starfleet.

Before serving on the Enterprise, D.O. served on the Daedalus-class starships Essex and Archon.

She went on her first away mission with Captain Archer to the planet Kaletoo during the Xindi mission in the Delphic Expanse in 2153, after several members of the crew fell into comas after an encounter with one of the Expanse's Orassin distortion fields.

She later provided the captain and several other crewmembers an escape from a Xindi trap while piloting Shuttlepod 2. (ENT novel: Last Full Measure)

She briefly served as acting executive officer/science officer, during Commander T'Pol's assignment to Vulcan, in 2155-2156.

In late 2156, she along with Malcolm Reed and Mike Burch, was promoted to lieutenant commander. (ENT novel: Beneath the Raptor's Wing)

Donna O'Neill has the distinction of being the first re-occuring book-only character to appear in the Enterprise novels, having appeared in all of Dave Stern's novels, as well as Last Full Measure, The Good That Men Do, Kobayashi Maru by Michael A. Martin and Andy Mangels, Beneath the Raptor's Wing by Michael A. Martin, and To Brave the Storm by Michael A. Martin.

She was created as a homage to a real-life Pocket Books staffer named Donna O'Neill. Series editor Margaret Clark has stated that the character as described in the books is the description of the real-life Donna O'Neill.

Enterprise (NX-01) personnel
Starfleet personnel	Almack • J. Anderson • Ansara • J. Archer • Billy • Bishop • K. Borovsky • M. Burch • Burrows • Carstairs • R. Chandra • Cole • Cook • Cravens • Elizabeth Cutler • Daniels • Diaz • Duel • J. Edwards • M. Fincke • Foster• Garver • A. Hart • Hess • J. Horn • Hutchison • Kelby • J. Kelly • Kimball • Ko • J. Lee • E. Leydon • T. Mayweather • M. McCall • Meir • E. Novakovich • D. O'Neill • Perkins • Phlox • Pointer • M. Reed • A. Rhodes • K.P. Ryan • A. al Saed • Santini • H. Sato • Stepanczyk • T'Pol • Tom • C. Tucker • Williams • unnamed Enterprise (NX-01) personnel
MACO contingent	D. Chang • C. Eby • S. Guitierrez • J. Hayes • N. Kemper • D. McCammon • F. McKenzie • M. Peruzzi