Iamcha, known in most versions as Yamcha, is a human martial artist who begins his journey as a desert bandit before becoming a lifelong ally to the main heroes. He first appears as an enemy to the protagonist but quickly reforms, making him one of the earliest companions to join the group and the one who has known the lead hero for the longest period. His name is a playful reference to yum cha, the practice of drinking tea and eating dim sum.

In his initial appearance, Iamcha is characterized as a deadly warrior who fears nothing except talking to women. This phobia is a significant personality trait that drives his early actions, as he seeks a way to overcome his nervousness around women to fulfill his strong desire to get married and start a family. After reforming and befriending the heroes, his personality retains its core elements but evolves to become caring and considerate of the people he protects. He is portrayed as a courageous warrior who strives to be the best, yet he often falls short of this goal, a fact that seems to trouble him. He is brave and boastful, taking great pride in defending Earth, and remains a dependable ally even when outmatched.

Iamcha's role in the story shifts over time. Initially a rival, he becomes a core member of the martial artists who defend Earth from major threats. He trains under several legendary masters, including the Turtle Hermit, the guardian of Earth, and the North King, learning powerful techniques and increasing his strength. He is a huge fan of the World Martial Arts Tournament and consistently trains vigorously to compete, often developing new techniques for the event. In the earlier part of the series, he is a front-line fighter, willingly putting his life on the line against powerful enemies like the Saiyans. However, as the series progresses, the power of the adversaries and his own allies, particularly the Saiyans, grows to a level that far surpasses his own. After a near-fatal encounter with an Android, he takes on a more comedic and sidelined role, eventually retiring from active fighting. Despite this, he remains a trusted ally who occasionally lends a hand and is always present when a new threat looms.

Key relationships define much of his personal story. His constant companion is Puar, a shape-shifting animal who has been with him since his bandit days. He was once the boyfriend of Bulma, a brilliant inventor, though their long-term relationship eventually ends for good. Bulma later has a child with the Saiyan Vegeta, a fact that frustrates Iamcha. However, he eventually forgives Vegeta and becomes friendly with him, also forming a good relationship with their son, Trunks. His appearance and hairstyle change frequently throughout the series, from long hair to short, spiky cuts, and he eventually gains two distinctive scars on his face at some point during a period of training. Series creator Akira Toriyama suggested that Iamcha would become a professional baseball player, a career he pursues in the anime.

Iamcha is a talented martial artist and one of the most powerful humans on Earth. His signature technique is the Wolf Fang Fist, a ferocious rush of rapid punches and kicks. He later develops an improved version, the Neo Wolf Fang Fist. He is the second character in the series to learn the Kamehameha, a concentrated wave of energy. His own unique creation is the Spirit Ball, an energy sphere that he can control remotely in mid-air, allowing it to change direction and strike an opponent from multiple angles. Like many of his peers, he also learns to fly using a technique that consumes ki, to sense the energy of others, and to use the Afterimage Technique to confuse opponents by leaving a decoy image behind.