Nappa

The Z Fighter's 'Comedian', Nappa doesn't seem to take many things seriously (in contrast to his rival Raditz). Vegeta, at one point, tried to avoid training with him. Nappa is considered a loyal Saiyan, however, even moreso than Goku. He is married to Vegeta with hybrid twins of his own named Potato and Tomato, then a son of Vegeta named Green.

Appearance
Nappa is a bald, clean shaven man who is fit due to randomly seeking out nearby gyms.

Personality
Goku's impure counterpart, he enjoys getting various reactions out of situations. Neutral morality playing pranks on Vegeta the most, although Goku is the one to fall for them. This is because Nappa isn't doing it to get on his nerves, he deeply cares for him.

Nappa gets serious during battles, developing his empathetic side more as the storyline progresses.

Background
Nappa was born into a noble family, and thus has a high ranking and power level compared to other Saiyans, automatically making him an upper level warrior. At a young age he battled alongside his Saiyan comrades during the Saiyan-Tuffle War.

He was a troublemaker, held back in Saiyan grade school. That's when he met Prince Vegeta and Raditz, befriending the juvenile delinquents. They formed a trio led by Vegeta.

Bardock's original special, Nappa gets Vegeta to take him to Dairy Queen.

Nappa was good enough (apparently as he most likely tricked the Dean) for being accepted into Saiyan University, becoming a Child Psychology Major. He minored in Pain.

At the time when Planet Vegeta was destroyed Nappa was in his 20s or 30s, he and the rest of Vegeta's group were away on a mission and did not return from the mission even when called back as Vegeta chose to ignore the message. When they received a message that Planet Vegeta was destroyed by a meteorite, Nappa wondered about Raditz and Vegeta's younger brothers but neither of them cared.

A few days before the destruction of Planet Vegeta, in Age 737, Nappa is seen watching the young Vegeta fight a group of Saibamen on monitor screens, and afterwards having a conversation about Frieza.

In an anime only flashback in the Frieza Saga, Nappa, along with Raditz and Vegeta return from their conquest on Planet Shikk. However, they are met with insult rather than congratulations by Dodoria, Zarbon, and Frieza. Nappa nearly loses control of himself and tries to attack Frieza, Zarbon and Dodoria, but Vegeta orders his comrade to calm and stand down, knowing that they would not stand a chance against them. Afterward, he then informs Vegeta that there was talk that, contrary to the reports about an asteroid collision blowing up the Saiyan race, it had in fact been Frieza who was responsible for Planet Vegeta's destruction, although Vegeta dismissed it, citing he didn't care and implied that the Saiyan race as a whole was weak for perishing.

Eventually, the three Saiyans come across a planet which they wish to conquer in order to sell for a high price, but the inhabitants prove to be much stronger than they had anticipated, so they temporarily abort the mission. However, they soon discover the location of Raditz's long-lost younger brother, Kakarot, who has been raised on Earth. While Raditz heads for Earth to intercept Goku, Nappa goes on to conquer another planet with Vegeta.

Dragon Ball Z Kai
The 2 Nappas meet, Vegeta hits Nappa calling him an 'idiot' for befriending the other Nappa.

Power
On-par with Raditz which forms their rivalry-friendship.

Like Vegeta, his tail was permanently removed in Namek.

Abilities
The Nappa and such...

Bulma
He quickly befriends her, constantly joking around mostly to annoy Vegeta. Bulma is an older sister to him, teaching him to differientiate between 'right and wrong'.