Buddy system - They're wise, loyal and often sassy. Black Best Friends help white heroines, but do they limit black actresses?

They're stars who have all played lead characters who experience adventure with the help of their BFF (Best Friend Forever). But in many cases, these BFFs might more accurately be characterized as BBFs -- Black Best Friend -- played by an African American actress whose character's principal function is to support the heroine, often with sass, attitude and a keen insight into relationships and life.

Celluloid BBFs have been featured in the just-opened "The Nanny Diaries," as well as "The Devil Wears Prada," and "Premonition." But BBFs have been even more of an influence in TV series, including "The New Adventures of Old Christine," "Ghost Whisperer," "Alias," "Ally McBeal," "Felicity," "Summerland" and "Private Practice," the spinoff of "Grey's Anatomy" premiering this fall.

The BBF syndrome isn't something that Hollywood likes to talk about, even as it continues to be a winking in-joke among blacks in the industry. One African American actress said that she and her actress friends tease one another about forming a support group for characters who had to help out their "woefully helpless white girls."

But on a more serious note, the trend of BBFs underscores the limitations that African American actresses still face more than five years after Halle Berry's Oscar-winning performance as best actress in a leading role for "Monster's Ball." Despite impressive résumés, solid credentials and successful achievements, many of the black actresses who have played BBFs are rarely offered the heroine role in mainstream projects. Not one black actress will star in a prime-time series on the four major networks this fall season.

And, as has been long lamented, lead roles in films are few and far between.

Rose Catherine Pinkney, executive vice president of programming and production for TV One, a cable network targeted to black audiences, was one of the few TV or film industry executives willing to talk about BBF syndrome, saying: "It's wonderful that studios recognize great talent. And there's more diversity, so it looks like the world. But it's a shame that studios also don't have the courage to put these actresses in leads."