Do you know who Enzo is?

Heading into tonight’s “Frasier” finale, here are some fun facts about the show:

• Only one regular character has been played by two different actors: Eddie, Martin Crane’s dog. He was originally played by Moose. After Moose retired, the role went to his son, Enzo.

• The original actress cast to play Roz Doyle was dropped in favor of Peri Gilpin, who had previously done NBC’s failed “Flesh ‘n’ Blood.”

Don’t feel bad for the first actress, though. That was Lisa Kudrow, who soon went on to star in “Friends.”

• Sharp-minded viewers might have noticed a flaw in the “Frasier” concept, Kelsey Grammer wrote in his autobiography: In “Cheers,” it had been established that Frasier Crane’s father was dead and he didn’t have a brother.

Grammer says he pointed that out to the writers: ” ‘We hadn’t really thought of that,’ they said. And then: ‘So we take license.’ ”

• Many viewers wonder about that big, ugly chair that Martin Crane lounges on. It really is comfy; we’ve tried it. And it really is ugly — now. Designers couldn’t find a chair that was ugly enough, so they bought a used one that was reasonably ugly, then added duct tape.

• The set design of Frasier Crane’s condo also tends toward accuracy. There’s a delicate Dale Chihuly glass sculpture on the fireplace which “does not come out until show time,” producer David Lee says.

The volumes in the bookcase are highbrow types, but the CDs are random. Frasier Crane might be startled to note that he has rock music in his living room.

• That really is Grammer singing the closing song and throwing in some words.

“I’ve had a secret fantasy all my life of saying ‘Good night! Thank you!’ — you know, rock ‘n’ roll,” he once explained. “And I did that after one of the tracks we recorded and the guys went, ‘Oh oh. There’s something!’ ”

He started throwing in other phrases, including “Frasier has left the building.”

Now we’ll see what he says tonight when “Frasier” leaves the building for good.