I don't know him/it
Je ne le connais pas personnellement.
I don't know him personally.
Je ne le connais pas si bien que ça.
I don't know him that well.
— Harry Potter et le Prince de sang-mêlé (2009)
Bien qu'il soit mon voisin, je ne le connais pas très bien.
Although he is my neighbor, I don't know him very well.
Tom est mon voisin, mais je ne le connais pas très bien.
Tom is my neighbor, but I don’t know him very well.
J'ai entendu parler de lui, mais je ne le connais pas personnellement.
I've heard of him, but I don't know him personally.
Je ne le connais pas vraiment, mais c'était un des garçons de Szilard à Chicago.
I don’t really know him, but he was one of Szilard’s boys in Chicago.
— Oppenheimer (2023)
I don't know him at all.