Many popular Breaking Bad characters are or have been part of Better Call Saul, but there's still several more major faces yet to show up. It's rare that a TV spinoff matches the acclaim of the original, but it could be argued that Better Call Saul is well on its way there. In many ways, it's a very different show than Breaking Bad, but as the seasons have gone on, more and more of the Breaking Bad feel has crept in, as Jimmy McGill gets closer and closer to his full and complete metamorphosis into Saul Goodman.
After five seasons, with a sixth on the way, Better Call Saul has now incorporated many characters first seen in Breaking Bad, both big and small. Besides Saul himself, Mike Ehrmantraut has been a regular since the beginning, and Gus Fring joined the mix in season 3. More recently Hank Schraeder appeared in season 5, alongside his DEA partner Steven Gomez. Tuco Salamanca also played a big role early on.
It's hard to imagine Better Call Saul season 6 - its final outing - not bringing even more Breaking Bad veterans into the fold. Here's some major names the spinoff prequel has yet to invite into Saul Goodman's tangled web.
Walter White (Bryan Cranston)
The obvious big kahuna of Breaking Bad characters that have yet to appear on Better Call Saul is Walter White, played by Bryan Cranston. The actor has said he's open to making a cameo on the prequel, but one assumes Vince Gilligan wouldn't sign off on it without a logical way to get there. During the main plot of Better Call Saul, Walt would still be a high school chemistry teacher, pre-cancer diagnosis. He and Saul hadn't met before he broke bad, so an earlier encounter wouldn't make sense. However, another flash-forward to the period around the time Saul changed his identity could conceivably include Walt in some fashion.
Jesse Pinkman (Aaron Paul)
Like Cranston, Aaron Paul has said he's open to making an appearance on Better Call Saul if he were to be asked to do so. The catch, again, is that in canon Jesse and Saul hadn't met prior to Breaking Bad, although Jesse knew of Saul from his reputation. A flash-forward cameo for Jesse wouldn't work from the same period as Walt, as Jesse was being held captive at that point. However, Jesse is still alive in the present, so he could theoretically encounter "Gene" from Cinnabon, as unlikely as that might be. Of course, Better Call Saul could dodge these issues entirely by showcasing Walt, Jesse, and Saul from an earlier spot in the Breaking Bad timeline, or having Walt and Jesse interact with characters besides Jimmy/Saul.
Skyler White (Anna Gunn)
Naturally, there wouldn't be any more of a logical way to explain having Skyler White appear on Better Call Saul and interact with its leads than there would be for Walt, at least not in the main timeline. At that point, Skyler is still a happy wife and mother with a loving husband and a normal family, albeit not without financial issues. One way she might appear on Better Call Saul without violating canon - which could also possibly apply to Walt as well - is by interacting with her brother-in-law Hank Schraeder, who's already joined Better Call Saul.
Marie Schraeder (Betsy Brandt)
Like Skyler White, Marie Schraeder was a character many Breaking Bad fans had a love and hate relationship with, whether that was truly fair or not. A compulsive shoplifter, Marie could be a bit grating, although she did clearly love her husband and family, and was absolutely shattered by Hank's murder near the end of Breaking Bad. With Hank already part of Better Call Saul, Marie appearing in a scene with him would actually make a lot of sense, and allow fans to see them back in happier times without violating the established timeline. Interestingly, Marie was planned to make a quick cameo during season 2, but it was scrapped.
Walter White Jr. (RJ Mitte)
As with his mom and dad, it wouldn't make any sense for Walt Jr. to interact with Jimmy/Saul in Better Call Saul's standard timeline, or really any other one, as they've never met. Considering Walt Jr.'s reaction to his father becoming a criminal and playing a role in his uncle Hank's death, it seems unlikely he'd look up any of his dad's old associates in the present day either. Like Skyler and Marie though, he could theoretically appear in a scene connected to Hank, at least one showcasing Hank outside of his job.
Todd Alquist (Jesse Plemons)
Jesse Plemons' loathsome Todd has yet to appear on Better Call Saul, and it's unclear how he could logically do so, although it was implied that he had dealings with Saul prior to his Breaking Bad introduction. Even if he doesn't show up on Better Call Saul, fans of the franchise at least got some more Todd via his surprisingly large role in last year's El Camino: A Breaking Bad Movie. Thankfully, Jesse got proper revenge on Todd in the series finale by murdering him, and their relationship was expanded in El Camino, allowing Plemons to really let loose with the character's creepiness and subtle menace.
Patrick Kuby (Bill Burr)
In all fairness, calling Patrick Kuby a major Breaking Bad character is probably pushing the definition of that phrase. He is, however, a fan favorite, thanks to the amusing efforts of actor and comedian Bill Burr. Kuby usually worked alongside Huell Babineaux as Saul Goodman's resident henchman, and Huell already recurs on Better Call Saul. Kuby was actually planned to appear in Better Call Saul season 5, but Burr was forced to back out due to wanting to be there for the impending death of someone he cared about. If he took the gig, he was certain he wouldn't have time to visit the person in question, and couldn't live with that thought. However, Kuby could still conceivably appear in season 6, hopefully once again with Huell.