Look on my Works, ye Mighty, and despair! Nothing beside remains.Percy Bysshe Shelley, Ozymandias
Yes. Dimmu Borgir are a black metal band, they have never stopped being one, and the people who say otherwise are almost always saying something else. The band play tremolo picked guitars over blast beats with a shrieked lead vocal, which is three of the five decisions that define the genre, and they have done it on every album since 1994 without a single change of direction. What actually happened is that they became large, and largeness reads as departure to an audience raised on the idea that obscurity is a musical value. Whether they are any good is a different question with a longer answer, and the honest version of that answer has nothing to do with genre at all. The neighbouring case, where a band genuinely did change what it was made of, is is Behemoth Black Metal or Death Metal.
Three of five, and three is enough
Take the five tests. The guitars pick rather than chug and leave the strings ringing: yes, on every record including the most recent. The drums blast: yes, at length. The lead voice is a high shriek placed against the instruments rather than a growl on top of them: yes. Where the band fail is on production, which is wide, warm and expensive rather than thin and hostile, and on structure, because they write verses and choruses and resolve them. Two failures out of five.
That is not disqualifying, because the production test was never absolute. Emperor recorded in a fifteen hundred seat concert hall in 1993 and nobody expelled them. Dissection made a clean sounding record in 1995 and it is on every list in the genre. Symphonic black metal is a real category with a real history, and the argument about whether a band with keyboards counts was settled thirty years ago in favour of the keyboards. Anybody who wants to remove Dimmu Borgir on production grounds has to remove half of the second wave with them, which is why nobody who makes the argument ever follows it through.

The two Norwegian albums the argument forgets
Before the orchestras there were two records made inside the scene itself and on its terms. For all tid was recorded at Stovner Rockefabrikk in Oslo between August and December 1994 and released by the German label No Colours on 15 March 1995, with Silenoz singing and Shagrath still behind the drums; Stormblåst followed on the small English label Cacophonous in 1996. Both are sung entirely in Norwegian, both are mixed with the keyboards sitting at the same thin level as everything else, and neither of them is meaningfully different in intent from what Gorgoroth or Enslaved were doing in the same eighteen months. Anybody who has only heard the band through a symphonic record made ten years later has heard the wrong band. Those two albums belong in any account of who to listen to from that period, and the second one is genuinely good.
The orchestra years
The transformation is a matter of budget rather than of genre. Enthrone Darkness Triumphant was recorded at the Abyss in Sweden by Peter Tagtgren and released by Nuclear Blast on 30 May 1997, the first album with lyrics in English and the first with Shagrath singing lead, and it is a well made record by any standard: the arrangements are tight, the keyboard writing is more sophisticated than anything else in the genre at the time, and the production is the first in Norwegian black metal that sounds like money was spent deliberately rather than reluctantly.
Then the scale kept increasing. Puritanical Euphoric Misanthropia was cut at Studio Fredman in Gothenburg across October and November 2000 with Fredrik Nordstrom, released on 20 March 2001, and used the Gothenburg Symphony Orchestra on eight of its eleven tracks with orchestration arranged and conducted by Gaute Storas. Death Cult Armageddon followed at the same studio in 2003 with the Prague Philharmonic and became the first Nuclear Blast release to pass a hundred thousand copies in the United States. Abrahadabra in 2010 used the Norwegian Radio Orchestra and the Schola Cantorum choir, more than a hundred musicians and singers in total, and reached number two at home and forty two on the Billboard 200.

A hundred musicians and singers, hired to fill a room that the songs had already left.
Where it stops, which is not where the genre stops
Here is the verdict, given once. Death Cult Armageddon in 2003 is the last Dimmu Borgir album with a reason to exist. In Sorte Diaboli went to number one in Norway in 2007, the first black metal album to manage that at home, and is the point where the writing starts repeating itself; the concept is more interesting on paper than the songs are on the record. Abrahadabra, made after the departure of the bass player who sang the clean parts and of the keyboard player, spends its largest resources on arrangement rather than on material. Eonian arrived on 4 May 2018 after eight years, charted well everywhere and split the reviewers straight down the middle, with one publication giving it full marks and another two out of five for using the orchestra as a substitute for atmosphere. In 2023 the band released an album of cover versions.
None of that is a statement about the musicians, who have kept a difficult operation running for more than thirty years and are better players now than they were in 1996. It is a statement about the records, which is the only thing worth being unimpressed by. A band can be entirely within its genre and still have stopped saying anything inside it, and the two facts have no bearing on each other.
The night the state orchestra turned up
In the spring of 1991 black metal in Norway amounted to a few dozen teenagers, a black painted basement on Schweigaards gate and a growing police file. On 28 May 2011, twenty years later, Dimmu Borgir walked onto the stage of the Oslo Spektrum with fifty three players from the Norwegian Radio Orchestra and thirty singers from the Schola Cantorum behind them, and the national broadcaster made an hour long documentary about it. The recording came out as Forces of the Northern Night in 2017. Whatever that concert was, it was not underground.
It was also not an aberration. Norway has spent the last fifteen years absorbing black metal into its official culture: the genre has its own category at the national music awards, Satyricon played with an exhibition at the Munch Museum, the National Library in Oslo mounted a black metal exhibition in April 2023, and the foreign ministry has briefed diplomats on the subject because the audience abroad matters. When somebody asks whether Dimmu Borgir are still black metal, a good part of what they are actually mourning is that answer: the music stopped being dangerous, and the band who benefited most from that are the easiest ones to blame for it. Neither the mourning nor the blame is a genre argument.
The verdict
Dimmu Borgir are black metal, specifically symphonic black metal, and the question is almost always a proxy for a complaint about scale, sales or the presence of an orchestra, none of which is a genre argument. The complaint that survives scrutiny is narrower and more damaging: a catalogue in which the last twenty three years have produced no album anybody argues about. Those are separate charges and only one of them sticks. For the bands that genuinely did walk out of the genre, in most cases while making the best music of their lives, the case histories are in black Metal Bands That Changed Genre.