What can I name the group of people those who are following a bad/corrupt leader, supporting his all kind of activities (even knowing their leader is corrupted) and never give up their leader with others in any arguments, as always saying that his leader is genuine.
I like Peter's suggestion of henchmen. Another alternative is cronies.
crony noun (pl. cronies)
informal, often derogatorya close friend or companion: he went gambling with his cronies.
The dictionary mentions this is often used as a derogatory term, so it conveys the negative sentiment you are looking for.
Incidentally, NOAD adds an even stronger label under henchmen:
Macmillan defines crony as:
crony noun a friend or supporter, especially of someone powerful
so the word also conveys the notion of supporting a leader. Macmillan adds a negative usage note, too, mentioning that the word is used for
You might like this term: Kakistocracy
From the link:
A kakistocracy (English pronunciation: /kækɪsˈtɑkɹəsi/) is a system of government which is run by the worst, least qualified, or most unscrupulous citizens.1 The word was coined as early as the 17th century. It was also used by English author Thomas Love Peacock in 1829, but gained significant usage in the 21st century.