Moira

From BioShock Wiki

Moira is Atlas' non-existent wife. Atlas frequently mentions Moira and his also-fictional son Patrick to Jack in order to gain his trust and sympathy. Atlas mentions to Jack in passing that he took Moira to the Fighting McDonagh on their first date. He also claimed that although she was a pain in the neck, she was a very beautiful woman.

He also explains to Jack that he brought his family to Rapture in the belief that they would have a better life there. He then asks, "can you imagine a bigger fool than that?"

Atlas enlists Jack into helping him "rescue" Moira and Patrick from a submarine they locked themselves in. When Jack reaches the bathysphere, Andrew Ryan sends splicers to destroy it. It explodes, leaving several unidentified Splicer corpses strewn in the wreckage. However, it is uncertain whether these were from inside the sub, or if they are just some of Ryan's goons. Atlas appears to grieve heavily over this, mostly to gain further sympathy from Jack, and his goal from that point of the game until his identity is ultimately revealed seems to be revenge.

There are also posters scattered about Rapture for a play called "Patrick and Moira", from which Atlas/Frank Fontaine likely got his inspiration for the fictional wife and child. One of these posters hangs on a wall of Atlas' headquarters in Hestia.