Mara Sov

Mara Sov is the queen of the Awoken in The Reef. Mysterious and cunning, she was regularly assisted by her brother, Uldren Sov, who acted as her confidant, enforcer, and adviser, before his death at the hands of the Guardian and Petra Venj.

Reef Wars
When the Fallen House of Wolves first attacked The Reef after the Queen interfered in their participation in the Battle of Twilight Gap, she defeated their then-current Kell. She offered the rest of the House a show of mercy and a home in the Reef, in exchange for their allegiance.

The Black Garden
Later, she and her brother assisted The Guardian in finding and activating a "key" to enter the Vex's Black Garden. In return, she demanded that the Guardian come to her aid if requested.

House of Wolves
Eventually, the House of Wolves rebelled against the Queen and left the Reef, killing some of her guards during their escape. The Queen offered the riches of her Reef as bounty for the traitors.

The Queen herself played no direct role in the quashing of the rebellion, up until the Guardian defeated the Wolves' new Kell, Skolas. Queen Mara and her Guard arrived and captured Skolas, imprisoning him in the Prison of Elders and rewarding the Guardian with the promised riches.

The Taken King
When Oryx's armies threatened the Reef, Mara Sov organized a frontal attack on the Dreadnaught, sending several Harbingers against the vessel, but to no effect. The power within was greater than the Queen could have imagined, and the Dreadnaught released a massive pulse that wiped out the attacking Awoken fleet, including the Queen's vessel as well as part of Prince Uldren's fighter squadron.

Forsaken
Mara Sov had not been heard from until Petra Venj and the Guardian gained access to The Dreaming City. It was there that Petra was able to make contact with the Queen, who tasked Petra with opening the City to the Guardians and slaying Riven.

Quotes

 * "I have shown you benevolence, Guardian. Should the Awoken ever need an ally I will call on you. And expect you to answer."

Trivia

 * Creative Story Lead CJ Cowan suggested in 2016 that Mara Sov may make another appearance at a later date: "This is totally spoiling, like, Destiny 2020 or something, but when we get to that world down the road where that original Pirate Queen comes out, I think it's going to be a really powerful moment."
 * This was confirmed by Mara Sov's appearances in the Dreaming City, as well as her interactions with the player.
 * Mara fully returned in Season of the Lost.
 * Mara Sov may have met the Exo Stranger, as she speaks of a friend who tells her that "a side should be chosen, even if it's the wrong side.", which is a quote that the Stranger is known to use.