(written from a Production point of view)
Frank Novak (born 4 March 1945; age 69) is the actor who played an alien businessman in the Star Trek: Deep Space Nine episode "Babel". His costume was sold off on the It's A Wrap! sale and auction on eBay. 
Born in Chicago, Illinois, Novak studied acting with TOS guest actor Jeff Corey. He made his film debut playing a loan shark in the 1987 horror movie Silent Night, Deadly Night Part 2, and would follow this with roles in such films as Newsies (1992, with Marc Lawrence), Sleepwalkers (1992, with Mädchen Amick, Alice Krige, and Ron Perlman), Carnosaur (1993, with Raphael Sbarge, Clint Howard, and Martha Hackett), Holy Matrimony (1994, directed by Leonard Nimoy and featuring John Schuck and Richard Riehle), the 1996 blockbuster hit Independence Day (with Brent Spiner, Bill Smitrovich, Leland Orser, Randy Nolen, Raphael Sbarge, Robert Pine, Randy Oglesby, and Erick Avari), Breat Men (1997, with Louise Fletcher, Matt Frewer, Terry O'Quinn, Raphael Sbarge, and Heidi Swedberg), and What's Cooking? (2000, with Alfre Woodard and Gregory Itzin). He also appeared in the 2000 independent feature Shadow Hours, starring Peter Weller, Brad Dourif, and Michael Dorn.
Besides DS9, he has made guest apparances on many other television series, including Quantum Leap (starring Scott Bakula and Dean Stockwell), The John Larroquette Show, Becker (with Terry Farrell), NYPD Blue (with Sharon Lawrence and Gordon Clapp), and CSI: Crime Scene Investigation.