Yekaterina "Katya" Derevko, alias The Black Sparrow, was the second of the three Derevko sisters to be introduced. She was a Colonel with the SRV (Russian Intelligence) and later allied with the Covenant.
Katya was sent by Irina to help Jack rescue Sydney and Vaughn from a North Korean prison (3.12). She confirmed Sydney's survival, but offered to help with her extraction on the condition that Jack murder Arvin Sloane as a "preventative measure." He agreed and she took Jack to meet her contact, Mr. Cho, to collect on a debt he owed her. When he declined, she stabbed his hand and ordered him to call Mr. Kwan.
When Jack went to Sloane's office to assassinate him, Katya called him to inform him, he was never safe - not even from his friends - and to back off of Irina. She then called Jack to tell him the plan was off (he was just a pawn to threaten Sloane). Following the mission to rescue Sydney and Vaughn, Jack confronted her about Irina's intentions. She told him that it would one day be clear to him and then kissed him passionately on the mouth before she walked away.
Later, while Sydney and Vaughn were on a mission to an inactive Russian bunker (to track down Sloane), Katya turned on her fellow Russian guards to aid in their escape (3.21). She revealed to Sydney that she was her aunt. She also told her that Irina had given birth to her sister, Nadia, in a Russian prison after she left Jack. Katya was helping Irina locate Nadia ever since; she discovered she had been snatched from the KGB by Vaughn's father. She was deeply distraught to learn that Nadia was currently with her father, Arvin Sloane.
Parents: Mother (name unknown, deceased), Father (name & status unknown)
Brother-in-Law: Jack Bristow (deceased)