Well-known (usually because they are memed online, or are seen as the major thinkers of anarchism)

Somewhat known (not known by people who know little about anarchism, but known well by anarchists or anarchist scholars)

Somewhat obscure (You likely will have to read back further in history or into a specific school of thought to see mentions of these people)

Quite obscure (will require a deeper dive into anarchist schools of thought, even if they did have an impact on anarchist thought)

Obscure (Only really known from reading works of other anarchist historians, and even then not a lot is known about them past some of their writings)