But it’s his resemblance to another police commissioner that has fans talking.
The 58-year-old Flatbush native tweeted a Throwback Thursday photo of himself side by side with the “Blue Bloods” actor.
“Hey #TomSelleck I think I have you beat on the mustache,” O’Neill wrote.
Selleck, who plays NYPD Commissioner Frank Reagan on the hit CBS cop drama, once told CBS2 he sometimes gets saluted by real NYPD officers when walking down the street.
O’Neill will take over as commissioner on Friday, Sept. 16.