Seinfeld is home to some of the most famously unlikable characters in the history of television. But the actors themselves are actually pretty swell.

Last week, writer and social marketing expert James Calder shared a story on Huffington Post about his father, Jim. Jim passed away earlier this month after battling a rare form of lung cancer, just three days before his 67th birthday. As that birthday approached, knowing how sick his father was, Calder and his wife Melissa started discussing what they could do to make it count.

It started with a Facebook group where Jim’s family and friends could post videos wishing him happy birthday, but the Calders wanted to go bigger. They decided to see if they could get cast members from Jim’s favorite show – Seinfeld – to join in the well-wishing.

“We never dreamed we would be able to get in touch with any of the top four lead actors on the show, let alone some of the actors who played supporting yet legendary characters.”

The Calders put their social marketing skills to work, and suddenly there was John O'Hurley offering a birthday greeting in character as J. Peterman. More videos followed. Here’s Patrick Warburton, in character as David Puddy, not only being delightfully dumb but also directly referencing Peterman’s video:

Then the names got even bigger. Here’s Wayne Knight as Newman:

Al Roker got in on the act:

And finally, in a culmination of this tremendous outpouring of support, Julia Louis-Dreyfus joined in on the fun (she’s not in character, but that doesn’t make it any less sweet).

You can view the rest of the videos (there are quite a few) over on Calder’s YouTube page. It’s so heartwarming, it’s almost enough to make George Costanza cry.