While Piccolo Jr. Is really just known as Piccolo in the rest of Dragon Ball, but for the original series it does make sense to be referred to as Piccolo Junior considering his father/original soul was King Piccolo.

He is born shortly after Goku kills King Piccolo and he shortly becomes a murdering machine as a little green dwarf.

But in a few short years, he grows up to be almost fully grown and participates in the World Martial Arts Tournament. One of his most impressive moves was reversing the evil containment wave against Kami.

His fight against Goku was epic and definitely more Dragon Ball Z than Dragon Ball in terms of style.

He was also the only contestant that didn’t really care about winning the tournament. All he wanted was Goku to die, for which “Ma Junior” almost succeeds.

Goku manages to win and is able not to kill him. As his death would technically disqualify him from the tournament and would result in the death of Kami and the inactivity of the Dragon Balls.

Goku even gives him a Senzu Bean so he can actually recover fairly easy. But instead of resuming the fight, he disappears for several years and thus is the start of Dragon Ball Z.