Sergio Leone

Frequently worked with Tonino Delli Colli and Ennio Morricone
Major characters' entrances are accompanied by variations of the theme music. [theme]
Invented the extreme close-up in western-style films. [close-up]
Showing ugly and violent acts with unglamorous simplicity
Long periods of silence followed by quick bursts of action

Although they did not work together until 1964, as children Leone and composer Ennio Morricone were classmates.
Composer Ennio Morricone has said that Leone asked him to compose a film's music before the start of principal photography - contrary to normal practice. He would then play the music to the actors during takes to enhance their performance.
Aside from saying 'Goodbye', Sergio Leone never spoke a word of English and always relied on a translator when talking to American actors. According to an interview with Eli Wallach, he spoke to Sergio in broken up French and discovered he is fluent in the language. This is how he communicated to Sergio Leone when shooting Zwei glorreiche Halunken (1966) ("The Good, the Bad and the Ugly").
Was sued by Japanese director Akira Kurosawa for remaking his Yojimbo - Der Leibwächter (1961) as "A Fistful of Dollars" (Für eine Handvoll Dollar (1964)) shot-for-shot without crediting him, and copyright infringement. The production of Für eine Handvoll Dollar (1964) apologized, compensated Kurosawa with $100,000, and 15% of box office revenues.
Clint Eastwood was amused by Leone's on-set behavior during their collaborations, having called the short, heavy Leone "Yosemite Sam" for his over-the-top temper and attempts to act like a cowboy through his thick Italian accent.

[on Henry Fonda] I have never known an actor with such craft, with such professional seriousness; such a pleasant man, full of humor, so reserved and so keenly quick-witted.
[on Lee Van Cleef] His glance makes holes in the screen.
In my childhood, America was like a religion. Then, real-life Americans abruptly entered my life - in jeeps - and upset all my dreams. I found them very energetic, but also very deceptive. They were no longer the Americans of the West. They were soldiers like any others...materialists, possessive, keen on pleasures and earthly goods.
[on Clint Eastwood] As an actor, he has two expressions: with and without the hat.
[on Orson Welles] He was a hard man. He'd lose his temper. He broke telephones. He also drank. But he could also be sensitive. [...] At any rate, I found him fascinating. I had infinite admiration for his directing.