Former president George W. Bush is this GOP race’s invisible man. (RON EDMONDS/AP)

Viewers of the approximately 3 million Republican presidential debates so far have come to expect certain things.

There’s the regular cast of characters, a moderator struggling to knock the candidates off their talking points, and loads of American flags.

But there’s one thing you’d be hard-pressed to find mentioned at a Republican debate.

George W. Bush? Who?

You’d think that the last Republican president--remember, that two-termer who’s only been out of the White House a scant three years--might come up frequently.

Not so. In fact, George W. Bush is the invisible man of the GOP race, the all-but-forgotten Ghost of Administrations Past. He’s its “He Who Should Not be Named,” in Harry Potter parlance.

According to a Loop analysis of the Republican debates, George W. Bush’s name has come up a pitiful 56 times. That includes mentions by all of the candidates in 16 major debates.

President Obama, on the other hand, got 560 name-drops.

But that’s not to say that the candidates didn’t have a Republican president at the tip of their tongues. Ronald Reagan, dead these last seven years and whose White House tenure ended nearly a quarter-century ago, by contrast, is a favorite topic--surprise, surprise--of the GOP debaters.

They invoked his name 221 times.

To put it in perspective, the year Reagan left office, Paula Abdul was a fresh-faced, chart-topping sensation instead of today’s former “American Idol” judge.

But in the GOP debates at least, he’s still in fashion.

Don’t feel too bad for Dubya. At least he got more attention than his father, who came up in the debates a mere two times.