Which character is killed in the Spanish Flu in season 2?

The Downton Abbey character killed by Spanish flu in season 2 is Lavinia Swire. She is Matthew Crawley’s fiancée and the daughter of the London solicitor Reggie Swire.

Lavinia first becomes connected to Matthew during the First World War, when he is serving in the British Army. She remains devoted to him after he returns badly injured and is told that he may never walk again. Her loyalty makes her relationship with Matthew serious, even as Mary Crawley’s unresolved feelings for him remain an important tension in the story.

During the 1918 influenza outbreak, Lavinia becomes ill while Downton has been affected by the epidemic. She overhears Matthew and Mary acknowledge their love for each other, then dies shortly before her planned wedding to Matthew. Her death is sometimes confused with Lady Sybil’s later death, but Sybil dies in series 3 from eclampsia after childbirth, not influenza.