Significant Mothers of Supernatural Part Two: The Surrogate
(For Part One: One-Hit Wonders go here.)

The Winchester Brothers have had their share of loss. Their family has never been large, forged more in arms than in blood, to be sure. From the first moment that the boys meet her, in her own way Ellen adopts the boys - tough-loving them as she does her own daughter. Throughout the series, Ellen has demonstrated many faces ranging from deft huntress to mournful mother. She serves to bring a maternal element to the series in mostly non-conventional, gun-slinging ways.

Ellen is first introduced to us in Everybody Loves a Clown as an old friend of John's who knows about the hunting life. When they first meet, Ellen is holding a gun to Sam when she realizes they are the Winchester brothers. Throughout season two, the Roadhouse and Ellen herself become a touchstone for Sam and Dean and what's nice is that with Ellen, what you see is what you get. Ellen Harvelle isn't a mother-figure in the traditional sense of the term. She's tough and does what needs to be done, many times disregarding her own safety in favour of protecting those around her. When we first meet Ellen, he has a daughter of her own and her first and fiercest loyalty is to protect Jo. In this respect, Ellen affords Sam and Dean more equal footing that her own daughter as a hunter and serves to be a sister-in-arms. Nevertheless, even older sisters have surrogate-mother tendencies (trust me, I know, it drives my brother nuts).

The respect Sam and Dean offer Ellen shines through at many moments in their relationship. Memorably, Dean's respectful fear for Ellen also comes through in the way he abides her authority in Simon Says he tells Jo he won't "run off" with her largely because of her mother, whom he claims to be afraid of. Actually, he seems to greatly respect her, similar to the way Sam and Dean respond to Bobby as an authority and grant him full respect.
Ellen's motherly instinct shows in "No Exit" when she calls Dean looking for Jo, not believing for a second that Jo went to Las Vegas. In "No Exit" we also learn that John was involved somehow in the death of Ellen's husband and what's admirable is that despite this, she continues to help his children. In fact, she didn't mention this to Sam and Dean - it was Jo who revealed this truth to them, perhaps to spare them (further) damaging the reputation of their deceased father?

The last appearance of Ellen is in AHBL:2 when Ellen turns up at Bobby's shortly after demons attack the Roadhouse, leaving nothing more than rubble. This is one of the few times we see Ellen's emotion as she and Dean embrace.  

Here, Ellen stands with the boys (one of many times) ready for whatever is coming. Like a mother, she also knows something about self-sacrifice and doesn't flinch when Jake has her point her own gun to her temple, threatening to kill her through induced suicide if Sam and Dean don't obey him. To this her response is simple - take Jake out and never mind what happens to her. At the end of "AHBL: P2," she still stands with the boys - no mention of them making a mess (as other characters do repeatedly throughout the series), just an offer to help them clean it up. A mother if ever there was.

Years later Ellen re-encounters Sam and Dean in "Good God, Y'All," again while holding a gun on them and throwing holy water on Dean - and like a true mother hassles them for failing to stay in touch, especially for not letting her know Dean was alive. 

 "Real glad to see you boys. [hug then slap] The can of whoop-ass I oughta open on you“ you can't pick up a phone?! What are you, allergic to giving me piece of mind?"
When asked if Ellen seemed a surrogate mother to the boys, Ellen's real-life counterpart recognized Ellen's role in the Winchester's lives:

"Yes, if I had to say in one way or the other...they definitely listened to Ellen and looked up to her. She was a living connection to their dad...they needed a mother type figure but on a regular basis, I was more of an equal to them in terms of my ability and knowledge of what was going on. (Supernatural Magazine, Issue #16)."

In the end, Ellen makes the ultimate sacrifice of her life for two reasons; her daughter, who is dying and whom she won't let die alone and to give Sam and Dean a fighting chance by kicking some hell-hound ass.

"I will always love you, baby." These are the last words Jo hears before she dies, cradled against her mother's shoulder just before Ellen blasts the hellhounds back to Hell. Truly the epitome of a mother's love and self-sacrifice for her child(ren).

What is consistent with Ellen throughout the series is that those she adopts are under her protection forever, regardless of circumstance or association. For a while, she was solid ground for Sam and Dean to regain their bearings and when it counted, she was always there with a helping hand. While not a mother to the Winchesters in the strictest sense, she is nonetheless a significant mother figure in the Supernatural world that touches the lives of Sam and Dean in considerable and powerful ways.