Benson appeared on "Buffy" from 1999 to 2002. The show, which featured Gellar as the titular heroine, wrapped up its seven-season run in 2003.
The actresses are to reunite during an upcoming episode of "Ringer," which premiered in September.
Benson will play a stripper who once worked with Gellar's character Bridget, the television news Web site said.
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