Gavin and Stacey's Nessa is set to switch on Barry's Christmas lights.
Ruth Jones, who played Nessa Shanessa Jenkins in the BBC sitcom, will return to the seaside town for the ceremony on 23 November.
The Bafta-winning show, about a long-distance relationship between a girl from south Wales and an Essex boy, was last screened in the UK in 2010.
In May it was announced it would return for a one-off Christmas special this year.
The lights switch-on will mark the end of a two-day festive market in Barry.
It will be followed by a free outdoor screening of the 1990 Christmas film Home Alone in the town's Central Park.
Over the summer, stars of the show, including Jones, James Corden, Rob Brydon, Matthew Horne and Joanna Page, were spotted filming scenes for the Christmas special in Barry.
Principle tourism officer for the town, Nia Hollins, said: "To welcome Nessa back to Barry on this festive occasion is very special indeed."
Gavin and Stacey, which was co-written by Jones, won best comedy performance at the Baftas in 2008.