While it's usually better about this than the other two "big three" shonen, there have been a couple of instances. With a cast this large, some One Piece characters are inevitably underutilized.
- The General Zombies from the Thriller Bark arc. The Elite Mooks of the island, they have hints of interesting pasts as they'd all apparently been a notable person in life, and several looked like they'd be good opponents for the Straw Hats (one had a physique similar to Franky's, another was a sniper like Usopp). Instead, they're unceremoniously pummeled into submission to show off the super-zombie Oars (the pummeling also takes place on a bridge, which proceeds to literally fall on top of them) The last two standing, hosting the shadows of Zoro and Sanji, don't even get a full fight, as Robin tricks them into taking each other out by exploiting their mortal counterparts' rivalry.
- When it comes to the 3 Sweet Commanders of Big Mom's pirate crew, a lot of people tend to poke fun at how useless Smoothie turned out to be for her Charlotte family during the Whole Cake Island arc. The other 2 commanders, Cracker and Katakuri, engage in full battles against Luffy, unlike Smoothie who simply follows the Thousand Sunny and attempts a couple of slashes in her giant form. This left many fans believing that Smoothie failed at living up to the hype as one of Big Mom's strongest crewmen. While she has won every minor fight she was in, she never had a big battle against any Straw Hat. Even when she's the only Sweet Commander to accompany Big Mom to Wano, she disappointedly gets literally kicked out of the conflict along with most of the crew.
- Toki is a time traveler who proclaims to have been born 800 years before meeting Oden, meaning that she was born during the Void Century, so some thought that she'd end up sharing important revelations about that time period. Toki's past unfortunately never gets any detail, and the only use she has for her Time Time Fruit is to send Momonosuke, Kin'emon, Kanjuro and Raizo forward in time, dying shortly afterward.
- Carrot was long thought to be a potential Straw Hat ever since she accompanied Luffy's group to Whole Cake Island, so a good portion of readers were disappointed by Carrot's lack of screen time throughout the Onigashima Raid and especially towards her and Wanda's offscreen loss against Perospero. Worse still is that she doesn't contribute much to the Raid after Nekomamushi defeats Perospero, and the fight itself was set up to be a way to resolve her emotional trauma surrounding Pedro's sacrifice. The plot thread of Carrot becoming the next leader of the Mink Tribe has been cited by some as a lazy attempt to consolidate her fans over her being sidelined and not becoming a member of the Straw Hats. Possibly the last straw for some fans was her not getting to say goodbye to Luffy and the others despite being with them for a good amount of time.
- The Time Skip hasn't exactly been kind to Smoker and Tashigi. Particularly during the Punk Hazard arc where even though the two of them got to play a major supporting role here, they were hit so hard with The Worf Effect that they constantly ended up on the wrong side of their encounters with Law, Caesar Clown, Vergo, Monet, and Doflamingo. It also didn't help that Smoker's major subplot of the arc where he goes after Vergo for making a mockery of the Navy ended up getting hijacked by Law.
