In the years after “Groundhog Day,” Harold Ramis and Bill Murray had a falling out that was only partially repaired by the time of Ramis’ death. But before that, the two Chicagoans and one-time Second City castmates were one of the funniest duos in film history.

“Bill was a strong man,” Ramis once told the A.V. Club. “He was a rock for us. You’d do a movie with Bill, a big comedy in those early days, just knowing he could save the day no matter how bad the script was, that we’d find something through improvisation. That was our alliance, kind of, our big bond.”

A ranking of their six collaborations:

1. “Groundhog Day” (1993)

Written by Danny Rubin, whose conception had a much heavier philosophical foundation, the movie was rewritten by Ramis, who also directed Murray as a cynical weatherman grudgingly taking a brainless assignment covering the groundhog’s appearance in Punxsutawney, Pa. Getting caught up in living the same day again and again provided both an opportunity for Murray’s caustic side (as his character first reacts angrily, then tries to commit suicide) and for his warm, Everyguy aspect as the ultimate redemption case. The movie seemed to resonate deeply with Ramis, too — after coming of age doing can-you-top-this outrageous comedy, he later became a (nonpracticing) Buddhist.

2. “Caddyshack” (1980)

Co-written with Douglas Kenney (a k a Stork from “Animal House”) and Bill’s ex-caddy brother Brian Doyle-Murray, the country-club comedy made excellent use of Bill and Rodney Dangerfield as the slobs who balanced out the gentry types played by Ted Knight and Chevy Chase. When Ramis, making his directorial debut, asked Murray to simply imagine his character enjoying a fantasy sporting triumph, the latter came up with his famous “It’s a Cinderella story” routine.

3. “Meatballs” (1979)

Ramis came in late to doctor a script (three others share credit) about wacky antics at a summer camp, and director Ivan Reitman, whose previous film (as producer) was “Animal House” thought Murray, then being underutilized on “Saturday Night Live,” would be perfect to star. Ramis later said Reitman wasn’t sure Murray was going to show up until the first day of filming. Murray’s anarchic, improvised “It just doesn’t matter” speech set the tone for his career — nutty, charismatic and too cool to give a damn.

4. “Stripes” (1981)

The one movie in which Murray and Ramis actually worked together as a duo, this Cold War military comedy suffers from a frantic action-flick third act, but made the most of Ramis’ laid-back sidekick (at a recruitment interview, his character says, “We’re not homosexuals but we are willing to learn”). And Murray dominated as the sad-sack soldier who winds up staying all night to motivate his troops to be . . . just barely good enough. Murray convinced director Reitman to cast Ramis as his best friend, knowing that Ramis would help him shine as an actor and punch up his lines.

5. “Ghostbusters” (1984)

The first comedy to gross $200 million in the US ushered in a new era of special-effects blockbusters merging comedy with fantasy. Co-written by Ramis, the movie was Dan Aykroyd’s idea and he intended it to star John Belushi. But when Belushi died, both Chevy Chase and Michael Keaton turned down the part of Peter Venkman. Then Murray came along with his slacker attitude and inimitable way with lines, like, “This chick is toast!”

6. “Ghostbusters II” (1989)

Uh, they also made this one.