‘Jeepers Creepers’ (2001)
‘The Chaser’ (2008)
‘I Saw The Devil’ (2010)
‘The Poughkeepsie Tapes’ (2007)
‘Dead End’ (2003)
‘American Psycho’ (2000)
‘Donnie Darko’ (2001; yeah, it’s in the sci-fi list… but it could fit into horror category -and others- perfectly just as ‘Mulholland Drive’)
‘The Hills Have Eyes’ (2006)
‘What We Do In The Shadows’ (2014)

Honorable mentions (maybe flawed, not ground-breaking or smaller ones but enjoyable films): ‘Identity’ (2003), ‘1408’ (2007), ‘Surveillance’ (2008), ‘The Signal’ (2007), ‘El Rey De La Montaña/King Of The Hill’ (2007), ‘The Last Exorcism’ (2010), ‘Los Abandonados/The Abandoned’ (2006), ‘Tucker And Dale VS Evil’ (2010), ’11:14′ (2003), ‘Eden Lake’ (2008), ‘King Of The Ants’ (2003), ‘The Exorcism Of Emily Rose’ (2005), ‘The Birthday’ (2004), ‘Willard’ (2003), ‘La Cueva’ (2014), ‘High-Rise’ (2015), ‘The Voices’ (2014), ‘The Visit’ (2015), ‘I’m Not A Serial Killer’ (2016), ‘Amer’ (2009), ‘The Lords Of Salem’ (2012), ‘Hobo With A Shotgun’ (2011) or ‘Tideland’ (2005).

I definitely would have found room for REC, I SAW THE DEVIL, and INSIDE.