Who you gonna call? Take your pick!
To celebrate Ghostbusters Day -- the anniversary of the original film's 1984 premiere -- the O.G. cast, including Bill Murray, Dan Aykroyd, Ernie Hudson and Annie Potts, reunited...and then united with Melissa McCarthy, Kristen Wiig, Kate McKinnon and Leslie Jones for a truly epic photo op.
"I mean, c'mon, how can this picture NOT make you happy? This is an epic group of people. Happy Ghostbusters Day!" Paul Feig, who directed the reboot, tweeted on Wednesday.
WATCH: Melissa McCarthy Responds to 'Ghostbusters' Online Haters: 'I Just Hope They Find a Friend'
The selfie also includes Ray Parker Jr., who performed the iconic Ghostbusters theme song, but is missing Harold Ramis, who died in 2014, and Sigourney Weaver, who does appear in the new film.
"Sadly, she was working on a movie in London and couldn't make it. But she was with us in spirit," Feig added of the get-together, arranged for Wednesday's episode of Jimmy Kimmel Live!
Meanwhile, ET spoke with Aykroyd on the red carpet at the Elle Women in Comedy event on Tuesday, where he gushed over the all-female cast of the reboot, which hits theaters on July 15.
"They're mega, mega brilliant stars," he said, adding that he "absolutely" loved their movie. "We respect the talent so much that for me, [it's] thrilling. They remember the old days, they remember the Tyrannosaurus."
Hear more of Aykroyd's Ghostbusters review and his message for online haters in the video below.