Regina Mills

Regina Mills is the main antagonist turned deuteragonist turned main protagonist of Once Upon a Time.

Background
Regina is the daughter of Henry and Cora. Around ten years old, she met her half-sister Zelena and the two became childhood friends, however, when they found out they were sisters, Cora cut their memories off, and forgetting they ever found each other ("Sisters") and Regina cannot stand her mother using magic on her whenever she disobeys her. It is also revealed she fell in love with Daniel, the stable-boy, and saved Snow White from her runaway horse. She hated her soon-to-be stepdaughter, Snow so much after it cost the death of Daniel when her mother took out his heart and crushed it.

Regina also kills her own husband with the help of the Genie who she turns into the Magic Mirror. After Leopold's death, Regina hunts her step-daughter, Snow White down, but fails to catch her every time. She later gets help from Tinker Bell, who helps her find her soulmate, who she is unaware is named Robin Hood of Locksley, also known as a thief. Her mother also tried to get Regina to have children of her own, but Regina refused to listen to her mother and took the infertility potion to prevent her from having any children.

She later poisons Snow with giving her the enchanted apple, causing her to fall into a death like sleep but the enchantment didn't last long as Regina realized that she could not get rid of Snow White, but let her go in exile, but Snow fought back, and a war was wagered against Regina and her ally, King George.

Regina soon lost the war and was captured by Snow White and her husband, Prince Charming. However, before she was executed, Snow stopped her execution, with the Blue Fairy stopping the arrows from flying. Later freeing Regina from her cell, Snow tested to see if the Queen could truly change. However, the evil queen took this advantage and stabbed her, but Regina was shocked that Snow could not be killed as Charming and Snow and their family, are under the protection of Rumplestiltskin's magic.

However, Regina found a loophole in this and threatened the kingdom with the Dark Curse, which she cast on the entire kingdom of the Enchanted Forest. She later became known as Regina Mills, ruling Storybrooke as mayor with an iron fist. She feels happiness for the first time when Owen Flynn and his father, Kurt. However, it takes a dark turn when they try to leave. Later, she adopted Henry after Emma gave him up for a closed adoption.