noun
minor villain; small-time crook; henchman
Refers to a petty criminal or a low-ranking member of a criminal organization, not a major crime boss.
彼はただの小悪党で、組織のボスではない。
He's just a minor villain, not the boss of the organization.
映画では、主人公が小悪党たちと戦うシーンが多かった
In the movie, there were many scenes where the hero fought small-time crooks.
大悪党 refers to a major villain or arch-criminal, the opposite end of the scale from 小悪党.
Compound of 小 (small, petty) and 悪党 (villain, scoundrel). The word 悪党 itself dates back to the medieval period, originally referring to bandits or rebels.