Style Classifications: Creator Owned Content/Licensed Properties
Notable Works: Sin City; Hellboy; Aliens vs Predator; The Mask
Up until recently, Dark Horse was the most important independent comic publisher in America. That title has since been taken by Image, but Dark Horse remains a success story for all times. This year marks their 30 anniversary, and for many years, they were the biggest rival---in terms of sales and stature---to Marvel and DC. In fact, they were the only rival.
Founded by Mike Richardson in 1986, the company was an offshoot from Richardson's 1980 gamble to open a comic shop in Bend, Oregon. He wanted to give artists a cushy-gig, so to say. They found early success with their Predator comics, and again a few years later with their Alien comics. By 1990, they had the market cornered with official Star Wars Universe books, and the leading edge of movie licensed properties was set.
Over the years, on the creator owned content side of the spectrum, they gave Matt Wagner a home for his Grendel series; Richardson himself loosed The Mask on the world; they let Mike Mignola create an entire Hellboy universe; saw the entire collection of Frank Miller's Sin City as well as his critically acclaimed story of Leonidas at Thermopolae in 300.
In those few well known works listed above, there are at least eight movies: two Mask movies (1994 and 2005), two Hellboy movies (2004 and 2008), two Sin City movies (2005 and 2014), and two 300 movies (2007 and 2014). (The second 300 movie is based on Miller's unpublished prequel about Xerxes.)
Chances are, if you don't know comics but can name one or two independent books not called Spawn or Walking Dead, you'll be familiar with Dark Horse's industry footprint.