Lance Henriksen stars as Frank Black in Millennium. Photo: Fox

Received wisdom decrees that Millennium, Chris Carter’s spiritual spinoff of The X-Files, was a flop. The show, which premiered during the fall of 1996, two nights before The X-Files’ fourth season kicked off, didn’t boast the 17 million weekly viewers its predecessor did (it had a still-admirable 7 million while airing during the 9 p.m. Friday-night graveyard shift); it didn’t accrue as fervid a fanbase; and it doesn’t have as catchy a mantra as “I want to believe” or “The truth is out there.” But comparing its impact and evolution to The X-Files, a prime-time phenomenon that has pervaded pop culture like an armada of colonizing aliens and reaches the end of its six-episode tenth season tonight, is unfair. A more apt comparison for Millennium, with its supernatural pseudo-sleuth and complex morality, is Angel, Joss Whedon’s less loved but more daring companion to Buffy the Vampire Slayer.

In Millennium, Reagan-era B-movie effigy Lance Henriksen plays Frank Black, a former FBI profiler who possesses vague psychic abilities. After professional and personal turmoil force him to retire, he joins an elusive independent group called Millennium, which specializes in unusual cases, usually of a potentially paranormal and grotesque nature. Black, who has no Scully with whom he splits his screen time, immediately differs from David Duchovny’s Fox Mulder — he’s a family man, residing in a yellow house under balmy skies, with a wife and young daughter — but has a similarly serene and observant disposition. The X-Files and Millennium also share writing/producing duo Glen Morgan and James Wong, writer Frank Spotnitz, director David Nutter, and Darin Morgan, who penned four of the best, most self-aware episodes of The X-Files, as well as a bunch of character actors.

Like Angel, its reputation remains tethered to its predecessor, but its posthumous legacy is more complicated: Some Carter acolytes consider it a mosaic masterpiece, a theological sci-fi-horror hybrid drawing from every major genre movie since the 1930s, whereas others dismiss it as a miserable abomination.

Though aspects of Millennium have dated (the entire series is rooted in a fear of the encroaching new millennium), it’s more prescient than it is antiquated. Carter, a New Age mystic who seems to genuinely believe that evil stems not from man but monster, got to wade in more sordid waters and dive deeper into darkness with Millennium than he could with the Über-popular X-Files. You won’t hear showrunners discussing its merits on commentary tracks, but its dark take on life and death, and the way it approaches the supernatural without fully committing to it, have seeped into other genre-mingling detective shows. The Grand Guignol horror and abstract, art-house-inspired visuals of Hannibal are of the same lineage as Millennium; the secret organizations and nebulous prophesies are all over Angel, particularly starting in both shows’ second seasons, as well as Fringe; and the sullen first season of True Detective, with its ciphers and symbols begging to be decrypted (but not explained), owes more to Frank Black than it does Mulder and Scully.

Millennium didn’t start off strong. The pilot, which is rife with cultural allusions, promises a pleasant mix of pretension and pulp, but the rest of the first season often succumbs to painful self-seriousness and doesn’t offer many profound insights on the nature of violence or evil. And the season has so much rape and incest and homicidal misogyny in it, some of the episodes make the infanticide of Morgan and Wong’s notorious “Home” look like Sesame Street. Angel, a more proper spinoff, similarly struggled to find itself during its first season. The show began to run concurrently with Buffy during the latter’s fourth season in 1999 (like Millennium and The X-Files three years earlier), and had way more arbitrary crossovers than either show needed, mostly to satiate heartbroken fans whose lockers were adorned with posters of Buffy and Angel. Angel (David Boreanaz), the vampire with a soul, was beginning to feel like a third wheel during Buffy’s spectacular third season.

But starting with its second season, Angel delves deeper into moral murkiness than Buffy ever dared. The show eschews Buffy’s black-and-white morality and instead lingers in ambiguity, as concerned with internal demons as it is external. In doing so, it found its soul. Then, abruptly, the season veers back into absurd comedy and ends with a four-episode arc in which Angel & Co. venture to a bizarre alien realm called Pylea, where people are cattle and Joss Whedon cameos as a dancing green idiot named Numfar. It’s a jarring tonal shift from the previous 18 episodes of brooding and bloodletting, but somehow it works, if only because everyone involved totally commits and Boreanaz gets to use his gift for deadpan stoicism.

Millennium’s second season had a similar turnaround. Carter, preoccupied by The X-Files’ fifth season and first feature film, handed off showrunner duties to Morgan and Wong, who jettisoned the series’ established mythos and turned the formerly benevolent Millennium group into an enigmatic, nefarious power whose tendrils seem to reach every corner of the earth, not unlike Angel’s fictionalized law firm, Wolfram & Hart. The season has a sealed-off quality and contains maybe the finest run of episodes Carter’s production company, Ten Thirteen, ever made. Without any major spoilers, things get apocalyptic as the Millennium group conspires to release a biblical plague on humanity because of something to do with Nostradamus’s prescience and Darwinism — it doesn’t make much sense, but this embrace of the absurd, of submerging completely into the silliness of Carter’s conspiracy stories, is what makes the season brilliant (and bananas). Whereas Carter took existence and destruction seriously, Glen Morgan, Darin Morgan, and Wong found a wry kind of fun in existentialism. (Darin Morgan’s “Somehow, Satan Got Behind Me” skewers Morgan’s own struggles with writing for Carter.)

Millennium’s second season also vaunts some of the best formal craftwork and visuals of any Carter show, with colors popping and chiaroscuro lighting casting Henriksen’s creviced face in expressionist shadow. (Its absence from all major streaming services and Blu-ray is a damn shame — illegal streams are a disservice to the show.) When Carter returned for the third season, like Morgan and Wong, he eschewed what came before, turning Millennium into a triptych show whose three seasons each feel as different as the three original Star Wars movies. The pontification on the nature of evil returns, and the Morgan/Wong banter is replaced by Carter’s macabre musings, but like Angel’s Pylea digression, it inexplicably works really well. The ratings, however, sank, and the show was canceled after three seasons. Frank Black got a sort of send-off in season seven of The X-Files, in which Mulder says he may be the best profiler to ever come out of Quantico. Henricksen wasn’t happy with the episode, which is now remembered for Mulder and Scully’s first true onscreen kiss. The episode, sadly, is a fitting way to say farewell to Frank Black, a man whose work usurping the End of Days was always overshadowed.