Killer Joe Piro. Wikipedia:

"a dance instructor to high society and popularized steps of the discotheque era of the 1960s and 1970s. He won his moniker at the dance contests that were a big feature of the New York City scene in the 1940s. The "Killer Joe" nickname comes from a supposed ability to wear out one partner after the other on the dance floor. It has been suggested that the John Travolta role in ' Saturday Night Fever' owes more than a little to Piro."

Looks like Barbara Feldon; can't find any proof one way or the other.