IX Equilibrium is the third studio album by the Norwegian black metal band Emperor, released on March 15, 1999 in Europe, and on April 27, 1999 in the US, through Candlelight Records.

Eduardo Rivadavia of AllMusic describes the album as a "sonic onslaught of nearly impenetrable proportions".

[1] He noted that drummer Trym "doesn't so much keep time as pummel his kit incessantly", while guitarists Ihsahn and Samoth "contribute an equally oppressive wall of sound laced with keyboard textures so demonic they were seemingly concocted by the great horned one himself.

"[1] He concluded, "Far from a masterpiece, but hardly a stinker either, IX Equilibrium falls quite short of the group's earlier albums through sheer lack of diversity, and will prove indigestible to all but the most committed black metal fans.

[3] In 2023, Rolling Stone ranked the album's opening track, "Curse You All Men!