Barber told Total TV Guide: “She’s popped up in several episodes, but until now you’re not sure who she is, or who she is even talking to.”
She added: “[Kovarian is] involved with Amy’s pregnancy, before and after the birth, and is in charge of a band of soldiers.”
Barber, who has made cameo appearances in four recent episodes, also praised her character’s unusual outfit.
“It’s a very fitted ’40s femme fatale look, but it has a futuristic twist,” she explained. “It’s a powerful, dominatrix look, though not in a sexual way. Doctor Who is a family drama!”
The Doctor Who mid-series finale airs this Saturday on BBC One in the UK and will air the following week on BBC America in the US. The show will return in late 2011