Professor Julie Langford
Professor Julia Langford is the scientist responsible for creating Arcadia, a garden and arboretum that supplies oxygen to Rapture. Although she loves the plants in Arcadia, she agreed to allow the park to become somewhat of a comodity, available to those who could pay. Her greed gets the better of her again when she and Andrew Ryan decide to sell the oxygen from her trees to the citizens of Rapture.
Andrew Ryan releases a chemical into the atmosphere that threatens to destroy the plant life in Arcadia. Jack, spurred on by Atlas, seeks out Langford to see if she can help. When you get there Andrew Ryan kills her. However, right before dying, she scrawls the combination to a safe on the window of her office. Inside the safe is the recipe for the Lazarus Vector, a concoction invented by Langford that promises to revive the trees.