The most common rendering is the word “salaud” ([salo]). It is also used as an insult.

(TLFi) B. 1. Surtout au masc., arg., pop., injurieux. Personne méprisable, dénuée de toute moralité; personne capable d’actes contraires à tous les principes moraux.

• C’est un salaud !
  (He is a bad man!)

• Salaud !
  ((You) dirty bastard!)

There is a much more vulgar term, “fumier” ([fymje]), (also used as an insult).

(TLFi) 2. Vulg. [Terme d’injure] Personne qui ne mérite que du mépris. Synon. ordure, salaud.

• C’est un fumier !

• Fumier !
  ((You) dirty bastard!)

The following terms from standard French are not vulgar but they have lost their force and are not used any more.

• canaille ((TLFi) B. Usuel. [Désigne des individus] Individu malhonnête et sans scrupules.)
• vaurien

To be consistent, considering that “bad man” is not slang but standard English, a word like “canaille” would be better. It’s a word we still find in a song by Gainsbourg, so it is not that much “out of fashion”.

There are words that have less general connotations of badness and refer to men specifically involved in illegal activity.

• voyou
• malfrat ((TLFi) Arg. et pop. Malfaiteur, voyou.)

“Glauque” is not used in standard French to say “bad”, except in a restricted part of the population, that is to say certain people such as those that like pornography; you find the term “femme glauque”; that is a name for a woman doing pornographic shows.

According to me, bad man is here not seems as an insult. I make a difference between “bastard”, where it would be seen as a real insult, and a bad man, a man without morality that think for himself and doesn’t care of others.
If you want to use an insult, I like the word “enfoiré”. It is an insult but it is also used when you want to say to someone like a firend, that he did something bad to you: “T’es un enfoiré mec, tu partages même pas la pizza!”. It is also used as a surprise word: “Enfoiré, elle est vraiment grande la tour Eiffel! “.

Without an insult, you have plenty of words. As there is a notion of beeing “rude”, I like the word: “caid”. “Caid” are people that think of himself as superior, but with the aura they have people tends to gave them respect, but more of fear than admiration.

With more context, like the full text of the musique, it would be easier to give a more appropriate word.

Figurez-vous que Bad man (Le titre du bouquin de Dathan Auerbach) n’a pas été traduit dans la V.F.
Est-ce un hasard si on le retrouve dans… How to translate the untranslatable de Jacques Bastin ?

Je crois que toute bonne traduction en français devrait prendre en compte le rude boys de la fin qui lui est rapporté.

Mais comme l’OP ne demandait qu’une traduction argotique… en voilà des possibles, fonction… du côté où on se trouve, du quartier où on se trouve et surtout… de l’époque. En vrac donc :

loub / peau-rouge / zonard / loubard / caillera / galapiat / arsouille / frappe / gouape / apache / marlou…

Sans connaître le registre de langage de l’expression anglaise, je traduirais volontiers presque littéralement par mauvais-garçon, qui n’est pas de l’argot.