Dende

Dende is Kami-sama's successor as the god of Earth. Like Piccolo and Kami-sama, he is also a Nameck-seijin, and is even younger than Gohan. Gohan and Kulilin first met Dende on their trip to Nameck-sei to gather the Nameck Dragon Balls. He has the power to heal injuries by laying his hands on the injured, and created more powerful Dragon Balls on Earth that can grant three wishes.

Nail

A minor character during the Nameck-sei episodes, Nail is the bodyguard of Saichoryo, the planet's elder and source of life for the Dragon Balls. He fused with Piccolo to give him a power-up to fight Freezer.

Trunks

Trunks is Vegita's first child. There are two different Trunkses in DBZ. (Yes, they are technically the same person but have totally different personalities.) Trunks is covered in more detail on the other character guide.

Artificial Humans #17 and #18

These two Artifical Humans were also created by Dr. Gero to kill Goku. They are twin brother and sister, #17 being a man with long black hair, and #18 being a girl with blond hair. In Trunks' future, they are both very much "bad guys," having wiped out most of the population of Earth. However during the altered timeline they are less destructive, focusing just on killing Goku. They end up joining the Z fighters to fight Cell, as Cell wanted to absorb both of them. Cell absorbed both, which was the last
time we ever see or hear of #17 until the very end of the manga series, but Cell eventually spits out #18. Later on after Cell is killed, #18 marries Kulilin.

Artificial Human #16

AH #16 is a very large robotic man with a red mohawk and green armor. He was made by Dr. Gero to kill Goku as revenge for destroying the Red Ribbon Army, but joined the Z fighters to fight Cell. He is normally very quiet and introverted, and possesses a strong love and respect for nature and life. His death at the hands (feet?) of Cell was what triggered Gohan to go Super Saiyajin 2 for the first time.

Mr. Satan

Used mostly as comic relief, Mr. Satan is the "hero of earth," taking credit for having killed Cell and saving the planet. Among "normal" Earthlings, he is fairly strong, but in reality he is a weakling and a coward. However, he performs the occasional heroic action, and occasionally manages to save the rest of the Z fighters by some minor action. He is also one of the only characters in the Dragon Ball series who has never died.

Videl

Videl is Mr. Satan's daughter, and is the same age as Gohan. While not nearly as strong as any of the other Z fighters, she is a lot better than her father. She is in Gohan's high school class and uncovers his identity of "Great Saiyaman." Eventually she and Gohan get married.

Son Goten:

Goten is Goku's second son, and a dead ringer for Goku when he was a little kid. At the end of the series, Goten was 17 and looked nothing like Goku though. Goten is very powerful for someone his age, although he is a little bit naive like his father. He can fuse with Trunks to become Gotenks, one of the most powerful characters in the series.

Maron

Maron is Kulilin and #18's daughter with a very round head and pigtails. She plays a very minor role in the series. (in fact, we don't even learn her name until long after she is first introduced) There's not too much more I can think of to say about her.

(East) Kaio-shin

Kaio-shin is one of four gods of the Kaios. Most of the other Kaio-shins were killed off by Majin-Buu, and one was
imprisoned within the Zed Sword. (we actually get to see this one) Kaio-shin then traveled to Earth to stop Babidi from reviving Buu, and en lists the help of the Z fighters. However, his plan to stop the revival backfires...

Kibito

Kibito is Kaioshin's assistant. He has the power to heal wounds with his hands much like Dende. He plays a fairly minor role in the DBZ series. Eventually using 15-dai-mae Kaio-shin's earrings, he fuses with Kaio-shin permanently.

Majin-Buu

Majin-Buu was one of the strongest villians in the Dragon Ball/Dragon Ball Z universe, but he eventually became a good guy. He has gone through more different forms than Freezer and Cell combined. The first Buu is fat Buu, a fat, round pink man with a cape and the mind of a baby, but is very strong. When he got really angry, the smoke that came out of his head changed into Skinny Buu. Fat Buu (who became a good guy around this point) tried to change him into a chocolate, but Skinny Buu blew the blast back at him. Fat Buu turned into a chocolate, Skinny Buu ate him, and turned into Super Buu.

15 Dai-mae Kaio-shin (lit. Kaio-shin from 15 generations ago)

15 Dai-mae Kaio-shin was the Kaio-shin trapped in the Z Sword. When it broke, he was released. Like Mutenroshi, he is a real pervert, but he has an interesting skill; he can give a huge power-up to anyone who can sit through a 25-hour power-up. He uses this skill to make Gohan the most powerful non-fused character in the series.

Gotenks

Using the Fusion, Goten and Trunks can fuse into Gotenks. Gotenks is very powerful, second only to Gohan and Vegitt, and also is the only character other than Goku that can change to Super Saiyajin 3. However, he has a huge ego which gets him in trouble . Gotenks is often used as comic relief as well.