Violet Crawley: The Dowager Countess and Lord Grantham's mother. She is determined to see her granddaughter Mary inherit the Crawley estate which would require that Mary wed Matthew, the heir presumptive, even though she doesn't approve of Matthew because he's only upper middle class rather than nobility. Violet is an old-fashioned matriarch, but also a totally hilarious mouthy badass.
Isobel Crawley: Matthew Crawley's widowed mother who moved with him to Yorkshire after he found out he was the new heir presumptive. Isobel is a trained nurse and was not content to sit at home all day, so she began working at the local hospital. Isobel isn't into the formal manners and values of the Crawley family -- something she has also instilled in Matthew -- so she and the Dowager Countess were frequently at odds. I have hopes that they will find common ground and become besties.