Look: Jennifer Garner wishes 'Alias' co-star Michael Vartan a happy 55th birthday

Nov. 28 (UPI) -- Jennifer Garner is celebrating Michael Vartan's 55th birthday.

The 51-year-old actress marked the occasion Monday by posting a tribute to Vartan, her ex-boyfriend and former Alias co-star, on Instagram.

Garner shared a throwback photo of herself and Vartan on the Alias set. The actress wears a blonde wig and Bavarian-style dress in the photo.

"I can't remember why I was Bavarian, but I do know today is your birthday. I hope it's a great one, Michael! XX S. Bristow," she captioned the post, referencing her Alias character, Sydney Bristow.

Garner and Vartan played Sydney Bristow and Michael Vaughan on Alias, a spy thriller series that had a five-season run on ABC from 2001 to 2006.

The pair also dated between 2003 and 2004.

Garner wished Vartan a happy 50th birthday in 2018.

Garner, Vartan, Victor Garber, Gina Torres and other Alias cast members reunited in 2021 for the show's 20th anniversary, as seen on Garner's social media.

"Since the end of the show, April of 2005, running into a cast or crew member from Alias has always led to this question -- When will you get everyone back together for a reunion? The 20th anniversary seemed like as good an excuse as any, so the call went out -- reunion party is happening, pass it on!" she wrote.

Alias was created and executive produced by J. J. Abrams.

Garner will next star in the comedy film Family Switch, which premieres Thursday on Netflix.