Here are a few of my choices:
{1} Lieutenant Kara Thrace ("Starbuck"), as portrayed by Katie Sackhoff in the rebooted version of "Battlestar Galactica," she is strong-willed and independent, plus it's suggested that she's sexually adventurous, I could envision her dishing out some serious corporal correction when she deems it justified or merely feels like doing so.
{2 & 3} Counselors Deanna Troi [Marina Sirtis] from "Star Trek: The Next Generation" and Ezri Dax [Nicole de Boer] from "Star Trek: Deep Space Nine," these choices superficially go against type since as therapists both are expected to be compassionate and soft spoken, however they would presumably administer a sound spanking if they felt it was in a Starfleet client's best interest. (Deanna also has the advantage of literally being an empath, so she can feel her spankee's reactions to his/her 'therapeutic treatment.')
{4} Sabrina Kane, the half-vampire, half-Mage ex-assassin and social rebel from five 'colorful' fantasy novels by Jaye Wells, she is formidable both physically and psychologically, plus her last name is a slight spelling variation of a classic instrument of corporal correction. (The first of the novels,
Red-Headed Stepchild, takes its title from an old expression dealing with the severe discipline of children.)
These are the ones I thought of on first impression...

--C.K.