Sam's Blurry Wife
In 15.20 Carry On, in the montage of Sam's life following Dean's death, we see him playing catch with his son, Dean. In the background, on the porch of the house, is a woman in a purple dress. Her features are too blurry to make out -- hence the name she was christened with. She is portrayed by Victoria Morgan.
In a private online meet and greet with Jared after a Creation Entertainment Virtual Fan Experience, a fan asked if this person was anyone specific. Jared apparently answered that no, this person's identity -- whom he referred to as Sam's wife or his child's co-parent -- was left open to fan interpretation.
- Sam's Blurry Wife on Tumblr