13. Stephen Moyer and Anna Paquin: 13 years
“True Blood” costars Moyer, 49, and Paquin, 36, started dating while filming the first season of the HBO show, which ran from 2008 to 2014. They were married in August 2010 and had fraternal twins, Charlie and Poppy, in September 2012. Moyer has two other kids, Billy and Lilac, from a previous marriage.
