The 50-year-old "Zoolander" star confirmed dating Glanville in '90s, during his appearance on "Watch What Happens Live," reported People magazine.
"Wow. It was short lived and it was fun, I wouldn't characterize it as a relationship. It was a couple of dates and fun. I'm not sure my wife (Christine Taylor) is even aware of that," Stiller said.
Brandi Glanville recently revealed that the two dated in the nineties.