Nappa has quite a destructive personality and loves demolition to an extreme level. When arriving on Earth, the first thing he asks Vegeta is if he can destroy a town. When taking time off to wait for Goku, Vegeta allows him to destroy as many things and places as he wants (in the anime only), as long as he does not waste enough energy to break a sweat. Nappa proceeds to demolish an entire Navy fleet division as well as an aerial raid, smashing through many jets and helicopters before leveling a slew of ships. Despite this, however, he usually congratulates his victims when they utilize attacks that come close to killing him, as evidenced when he congratulates Tien Shinhan on his use on a Spirit Tri-Beam that shattered his Battle Armor, citing that, had his aim been better, it would have severely injured him.

Nappa also has a very cocky personality, as he enjoys toying with his opponents. Nappa is somewhat sadistic, and his sadism is strongest by far towards Goku, and he repeatedly voices the intention to kill Goku's friends and son before his eyes as revenge for his treason towards his own race (by siding with Earthlings instead of the Saiyans). He tends to fight first and makes use of his brawn more so than his brain. However, his great ego would immediately vanish the second someone causes him a bruise or scar, and would decide to kill them slowly and painfully as a result. He is, in this instance, vain to the extent that he feels his appearance should remain unscathed (though in the Japanese dub, his rage against Krillin is fueled by the blow to his pride over being wounded by a much weaker opponent). However, he would still eliminate anyone as quickly as possible when losing patience with them.

Oftentimes, he allows his anger to get the best of him, becoming extremely enraged and infuriated and unable to think properly, which results in Vegeta constantly reminding or, in some cases, ordering him to calm down. Whenever Vegeta tells off Nappa for acting asinine, or not listening, Nappa apologizes to Vegeta, usually in a slightly fearful state, and then proceeds to claim he was not thinking straight, showing his respect for Vegeta. In the Japanese dub, Nappa normally addresses Vegeta in a casual manner. In Bardock - The Father of Goku, this is alluded to be Vegeta's preference when he orders Nappa to "quit bootlicking". However, whenever chastised by Vegeta, he always addresses him with very polite language, as one would normally address a superior. It is only when Vegeta decides to kill him that Nappa abandons all respect for him, even calling Vegeta a "dirty rat" (though only in the Ocean dub) and challenging him in Dragon Ball GT. Despite many years of loyalty, Nappa also seems to never like working with his those superior to him such as Vegeta possibly due to the fact that Nappa doesn't like being in servitude (as that is a common trait among Saiyans working under Frieza) and is capable of going as far as killing a superior he dislikes if given the opportunity. This is evidenced in the fact that in a what-if scenario in Dragon Ball Kai: Ultimate Butōden, Nappa defeats Goku under orders from Vegeta and decides to rebel against Vegeta. Both combat each other and Nappa defeats Vegeta, afterward killing Vegeta with his Volcano Explosion attack similarly like how Vegeta killed Nappa with his Galaxy Breaker in the original. Nappa also calls Frieza a jerk in Dragon Ball FighterZ after being scolded by him showing that despite his loyalty, he still thinks low of his superiors though still maintains some form of respect toward them.

An anime-only flashback in the Frieza Saga, shows a more sympathetic side to Nappa. He appears to be shocked when Vegeta claims not to care about the death of his father and the rest of the Saiyan race, and his overall dialogue seems to imply that he does not kill when there is nothing in it for him, once even nearly attacking Frieza, Zarbon and Dodoria when they mocked them in how long it took to take out Planet Shikk instead of rewarding them for their task, with only Vegeta stopping him. Also, when Nappa and Vegeta learn about the Dragon Balls and their wish-granting capability, Nappa's first suggestion is to bring Raditz back to life, demonstrating that despite his ruthlessness, he cares for his friends and comrades. In the manga and anime Nappa's ideal are often geared toward the greater good when put into thought, this is shown to where he suggest on putting priority in repopulating with the people of Earth in hopes of cultivating a new Earthling/Saiyan Hybrid race however Vegeta opposes to the idea much to Nappa's dismay (though ironically Vegeta himself would later settle down on Earth and ended up having a hybrid son with Bulma and later a daughter as well, though Nappa himself is hostile towards Vegeta's son as well as his son from the future in various video games due to them being related to the backstabbing Vegeta). Within a filler episode, Nappa is interested in being titled "A hero" by the remaining Arlians and doesn't feel it bad to do a good deed (possibly even considering to spare Arlians their planet), however Vegeta opposes which revealingly disappoints the Saiyan.