Vice President of Farrow-Marshall and loyal assistant to Baal. Mayfield held a brief meeting with Samantha Carter to assure the Air Force that the company was co-operating with the authorities regarding Alex Jameson's disappearance. She dismissed local sightings of activity at their closed plant in Edison, Virginia, insisting that the company had not had need for the facility after it had ended the jobs of 800 employees.
As the closest of Baal's personnel during his time on Earth, she was aware that he possesses "supernatural" abilities like making his eyes glow. Mayfield may have originally been serving Baal as the equivalent of a lo'taur servant, who is out for personal gain. She also maintained relationships with Baal's clones, seeing to their various needs.
Mayfield herself was later revealed to be host to the Goa'uld Athena. But it is likely that she became a host only after fleeing into hiding with Baal when he was discovered, as Samantha Carter did not report sensing the presence of a symbiote at the time of their meeting.
Ex Deus Machina - Mayfield fields questions from Samantha Carter before abruptly dismissing her, maintaining her allegiance to Baal and his clones.
Memento Mori - Mayfield captures Vala Mal Doran and subjects her to interrogation, revealing herself to be the Goa'uld Athena.