Getting a handle on Actor Guardians Of The Galaxy resources
Most people who come looking for this are either casting directors trying to track down headshots, or fans who want to dig into production details that never made it into the final cut. Either way, you need a reliable source because a lot of what floats around on forum boards and fan sites is outdated or straight-up wrong. The official route is still through the studio press materials and the verified IMDbPro pages for the principal cast. Chris Pratt, Zoe Saldaña, Dave Bautista, Bradley Cooper, and the rest have updated profiles there that include current representation, showreels, and recent credits. That last part matters because several of these actors have been bouncing between projects, and if you're trying to book something similar or reference their filmography, you want the most current data possible. I spent about three weeks tracking down updated call sheets and on-set photography from the first two films for a behind-the-scenes article I was editing. The problem was that most of the images circulating online had been stripped of metadata during multiple republishes across fan sites. What I ended up doing was going directly to the photographers who worked on set — people like James Qualter and Matt Schwarz — and requesting the high-res files with full credits intact. Their websites had proper EXIF data and licensing info that you couldn't get from any aggregated gallery.
For the third film and beyond, Marvel Studios started releasing more official press stills, which helped. But even then, the scheduling photos and wardrobe references tend to live in production departments rather than public domains. If you're looking for those specifically, you usually need to go through the art department contacts listed on the film's LinkedIn page or reach out to the production coordinator via Industry City or similar platforms.
Common mistakes people make when searching
One thing I see constantly is people using Google Images and assuming the first result is accurate. The actor swap problem is real. With CGI-heavy franchises like this, face references and motion capture work means that what you're looking at in promotional material might not even be the principal actor in certain shots. I ran into this when trying to identify a specific stunt double for one of Bautista's fight sequences. The publicity stills showed him clearly, but the actual stunt work was handled by a different person entirely. Cross-referencing with the on-set crew lists from SAG-AFTRA disclosures and the stunt coordinator's own website sorted that out in about ten minutes. Another issue is the reliance on Wikipedia for actor biographies tied to this franchise. The infoboxes are frequently edited by fans who mix up release dates, confuse voice work with on-camera presence, or list uncredited roles as if they were featured. For instance, Pom Klementieff's Mantis appearance timeline got mangled in several versions before stabilizing. Always verify against the actor's official site or IMDbPro.
Get the Full Details

What actually works for detailed research
If you need comprehensive data — and I mean comprehensive, not just a list of names — the combination of IMDbPro plus the above mentioned production photographer archives is probably your best bet. Add in the Art of movie books published by Fantagraphics or IDW, which sometimes include credit lists and production notes that aren't anywhere else. Those run about thirty to forty dollars each but they save you hours of digging. For casting purposes, the talent agencies represented by the principal cast are the place to start. William Morris Endeavor, Creative Artists Agency, and others have publicly listed rosters. You won't get personal contact info without a legitimate professional inquiry, but knowing who represents whom cuts the guesswork significantly. I once wasted two days trying to reach someone's office only to find out they'd switched agencies six months earlier. A quick search on the agency website would have saved me that. The bottom line is that Actor Guardians Of The Galaxy as a search term pulls up a lot of noise. The people who actually worked on the films — producers, coordinators, photographers, agency reps — are where the clean data lives. Everything else is secondhand at best.