Samantha Clayton

An unnamed woman was the subject of an affair with Oliver Queen, causing him to cheat on Laurel Lance. He ultimately got her pregnant, though she was paid $2 million by Moira Queen to pretend she had had a miscarriage and move back to Central City.

Affair with Oliver Queen
In 2007, the girl was the first of two known women with whom Oliver cheated on Laurel (the other being Sara Lance), but he accidentally got her pregnant. Oliver became distressed when he learned this and told his mother. Moira brought the girl over to discuss the matter and made her an offer: 1 million dollars to tell Oliver that she had lost the baby and another $1 million to move to Central City and never speak to him again, to which, after some uncertainty, she agreed. Later, she told Oliver the "bad news" over the phone, and he was both saddened and relieved that he wasn't going to be a dad, unaware of the truth.

Crossing paths with Oliver in Central City
In late 2014 the woman stopped by CC Jitters one day where she bumped into Oliver. She said she was sorry for what happened to Moira, and he in turn apologized for not getting in touch with her after their affair which she understood. He conspicuously failed to mention her name, or introduce her to Felicity, Barry and Iris, who were with him at the time; he simply told Felicity she was someone he used to know. As they left, the woman called her child and told them she'd be home soon with hot chocolate, as she looked at Oliver one last time.

Behind the scenes

 * In the DC comics universe, Oliver illegitimately has a child, Connor Hawke, with a woman named Sandra. Connor would go on to succeed Oliver as Green Arrow.
 * The role is listed on IMDb as "Sandra Hawke", but this is never confirmed onscreen, hence the unnamed nature of the character.