Robert, Earl of Grantham and Cora, Countess of Grantham
The kind-hearted Robert (Hugh Bonneville) originally married American heiress Cora (Elizabeth McGovern) for her money, but the relationship blossomed into true love (they even sleep in the same bed! Upper-class faux pas!). Though Season 2 sees their marriage turn a bit frosty.
Lady Edith, Lady Mary and Lady Sibyl
Mary (Michelle Dockery, center) is the eldest and somewhat cold one. Sibyl (Jessica Brown Findlay, right) is the youngest and rebellious one (entertaining a romance with the socialist chauffeur, Branson) and Edith (Laura Carmichael, left) is the middle daughter and ... there also.
Violet, Dowager Countess of Grantham
Robert's stern, loose-lipped and sassy mother, Violet (Maggie Smith) butts heads with everyone while still ruling the town (don't mess with her at the Downton flower competition).
Matthew and Isobel Crawley
Robert's distant cousin, the snobbery-averse Matthew (Dan Stevens, above left) is brought in as the Grantham heir after two members of Robert's family die in the Titanic. Falls for Mary, who wants nothing to do with him until it's too late and he finds not only a different fiance but ships off to WWI. Mother Isobel (Penelope Wilton), a passionate nurse and volunteer, spends most of her time in a match of wits with Violet, of course.
Carson (Jim Carter, above) is the butler, in charge of the male staff. Also, has a soft spot for Lady Mary.
In charge of the female staff, Mrs. Hughes (Phyllis Logan) is, like Carson, utterly devoted to Downton (she turned down a marriage proposal to stay on staff).
John Bates and Anna
Our favorite couple, the moral Bates (Brendan Coyle) comes to Downton as Lord Grantham's valet (he dresses him and such) and instantly falls for the sweet, caring Anna (Joanna Froggatt). Their relationship is tested in Season 2 by the meddling of the evil Mrs. Bates.
O'Brien and Thomas
The malcontent duo of the staff, O'Brien (Siobhan Finneran), the countess' maid, and closeted gay Thomas (Rob James-Collier, originally a footman, then he went to war and returned to Downton to help oversee the part of the house converted to a convalescence home for injured WWI soldiers) spend much of their day doing the following: smoking, spying on everyone, smoking, insulting people and insulting people while smoking,
The scullery maid (think grunt work: dishes, dusting) under the watch of flighty cook Mrs. Patmore, Daisy (Sophie McShera) has had quite a dramatic time at Downton: she falls for Thomas (good luck with that), nearly poisons the Crawley family and is forced into a beyond uncomfortable situation with footman William.