This poster, based on a famous photograph from Ebony
, popularized the slogan.
By any means necessary is a translation of a phrase coined by the French intellectual Jean Paul Sartre in his play Dirty Hands. It entered the popular culture through a speech given by Malcolm X in the last year of his life. It is generally considered to leave open all available tactics for the desired ends, including violence; however, the “necessary” qualifier adds a caveat—if violence is not necessary, then presumably, it should not be used.
Jean Paul Sartre 
The phrase is translation of a sentence used in French intellectual Jean Paul Sartre's play Dirty Hands:
I was not the one to invent lies: they were created in a society
divided by class
and each of us inherited lies when we were born. It is not by refusing to lie that we will abolish lies: it is by eradicating class by any means necessary
—Jean Paul Sartre, Dirty Hands: act 5, scene 3. 1963
Malcolm X 
It entered the popular culture through a speech given by Malcolm X in the last year of his life.
We declare our right on this earth to be a man, to be a human being, to be respected as a human being, to be given the rights of a human being in this society, on this earth, in this day, which we intend to bring into existence by any means necessary.
Mandela case 
In the final scene of the 1992 movie Malcolm X, Nelson Mandela—recently released after 27 years of political imprisonment—appears as a schoolteacher in a Soweto classroom. Yet Mandela informed director Spike Lee that he could not utter the famous final phrase "by any means necessary" on camera fearing that the apartheid government would use it against him if he did. Lee obliged, and the final seconds of the film feature black-and-white footage of Malcolm X himself delivering the phrase.