If we're going into electronic music, then I'll nominate the original M-Plant pressing of Robert Hood's 'Internal Empire', but that's only the tip of the Detroit iceberg.
Just about all the releases Hood and Mills did under 'H&M' were labelled as EPs. 'Drama EP' is a favourite of mine, and there's 'Tranquilizer under 'H&M', then Jeff Mills's 'Tephra' and 'Mecca'. All of these are on Axis, and I mention them because they all use EP in the title, which isn't that common for dance music 12"s.
I'll come to Drum and Bass in a bit.