But I read all the books

That you should know professor Black, right?

I know him. They brought his painting along on the horcrux hunt and he aided Them. He also reported to snape where they were so he could give them the sword of Gryffindor. He was also the headmaster but loathed his job.

He is actually *is* in the movies though but they never really talk about him.

I wonder why they would cut that out. It was such a good part of the book.

All correct! Indeed, it makes a very big question. All that happens in the books is that Dumbledore tell him to report to Sirius and Molly that Arthur Weasley was injured (when Harry saw him through Nagini's eyes), but is then not even addressed by name.
In the movies people who didn't read the books would wonder how Snape found them so he could hand them Gryffindor's sword (he heard Hermione mention the location).
Although he was (according to Sirius) the least popular headmaster Hogwarts ever had, he was a very brilliant character who did expose Harry's flaws with ease (even though it was a bit of a biased opinion). Also professor Black exposed a part about Snape. Although Snape loathed Hermione he did not tolerate Black calling her a "Mudblood" (due to the way he lost Lily as possible mate for good). It was really a pity he was left out.

It really is. Have you noticed that on all the potterheads unite memes we leave the most thorough answers

Although this guy *is* appearing in the movies, he gets no attention at all and in book 7 his role is actually very important. As a matter of fact, he was the reason Snape knew where Harry was so he could he lure him with his Patronus to the Sword of Gryffindor, for starters. (In the films that part is completely omitted, and you could wonder how Snape could find Harry to lure him with this Patronus).