Doctor O'Neil was a character cut from Aliens early in its production. In the final film, his role and dialogue was assigned to Carter Burke, although unlike Burke, O'Neil notably never left Gateway Station (known as "Earth Satellite Station Beta" the original treatment) and did not accompany the Colonial Marines to LV-426.
O'Neil was a doctor stationed aboard Earth Satellite Station Beta who served as Ripley's primary point of contact in the early part of the story. He reintroduced Ripley to Jonesy and also helped her to get in touch with her daughter, who was still alive but old and crippled in this version of the story. O'Neil guided Ripley through the inquest aboard Station Beta, and after Ripley was stripped of her flight status, he helped her to get an apartment on Station Beta.
O'Neil later accompanied Lieutenant Gorman to Ripley's apartment after contact with the colony on LV-426 was lost. While Gorman tried to convince Ripley to go, O'Neil offered to look after Jonesy in her absence. As in the film, Ripley refused, and this was the last appearance of O'Neil — after her nightmare, Ripley called Gorman to agree to joining the mission.