Star Trek is one of the most beloved franchises in television history. That doesn’t mean it has been without its share of controversy–from the production staff to the fans to TV networks. The most controversial episodes are discussed below.

With its classic time travel story, this episode is widely considered one of the best in Trek history. However, behind the scenes, it caused a firestorm between the producers and the writer. Harlan Ellison, a noted sci-fi author who penned the episode, was upset with the changes Gene Roddenberry and D.C. Fontana made to his story. These included the excision of a drug addicted Enterprise crewman and a hostile Kirk-Spock relationship. Ellison wanted his name removed from the final episode, but Roddenberry wouldn’t do it. There was bad blood between the two for years. In 2009, Ellison sued Paramount for failing to compensate him for all the decades of merchandising the studio did for the episodes. An LA federal court ruled in his favor.

First episode of third season, and the first to air after the series was renewed. Too bad it would end up considered the worst Star Trek episodes of all time. As the title would suggest, it concerns Spock’s Brain–it’s gone missing, and the crew must find it. Leonard Nimoy says he felt embarrassed throughout the episode, though it’s possible to look back on the episode and think it’s so bad it’s good.

Under the control of aliens, Kirk and Uhura kiss. It just so happens that Kirk is white and Uhura is black. Though often called the first interracial kiss on TV, it wasn’t; the kiss wasn’t even voluntary. However, NBC was frightened at the potential that southern TV stations would be angered by the kiss, and they did two takes, one with the kiss and one without. Only Nichelle Nichols, who played Uhura, deliberately flubbed the latter take, so the kiss remained. There isn’t any evidence this show caused any real controversy when it aired, save for a single irate letter from a Southerner.

Parasites infect the Federation, threatening to take it over. The controversy comes from a particularly violent scene at the end of the episode. Picard and Riker confront Remmick, a Starfleet officer infected by the parasites. They shoot him with phasers, causing his body to explode, and revealing the mother bug inside. This scene was so violent that the BBC removed it when airing the episode, and the Canadian sci-fi channel still runs it with a warning.

Star Trek’s only clip show. Riker falls into a coma and the only way to save him is have him relive painful memories. Paramount told the makers they wanted to do a clip show because other episodes had big budgets. And thus this was born. Even a co-writer thought it was pretty bad, calling it a “piece of shit.”

This episode concerned terrorism and a planet who wants the Federation to join their fight for freedom. Again, the Brits are to blame for the controversy. Data has a line in which he says Ireland was eventually unified by terrorism in 2024. Sensitive about such a mention when the Troubles in Northern Ireland were still ongoing, the BBC cut the line when the episode first aired. The episode has never been shown on Ireland’s RTE channel, and sometimes when the episode is aired the UK the line is still cut.

Star Trek is infamous for avoiding overt references to homosexuality, something fans have complained about for decades. This is one of the few episodes to make even an oblique reference to it, showing a female kiss. Jadzia Dax and Lenara Kahn are Trills, an alien species that lives on in symbionts implanted in host bodies. Two of their previous hosts had a romantic relationship that was never resolved, hence the same-sex kiss. One TV station in the south removed the scene, and the producers received a large number of negative calls in response.

Notable because most of the controversy happened before the episode was aired. “To the Death” was the first Star Trek episode ever cut for violence. When the DS9 crew travel to a planet with an Iconian Gateway–a portal to practically anywhere–they encounter hoards of the vicious Jem’Hadar. Hand to hand combat ensues. Originally, 52 Jem’Hadar were shown getting killed, but this was was trimmed to 20, losing 45 seconds of the episode. The BBC censored it even further. Fans complained the result felt choppy and disjointed.

Seven of Nine is forced to compete in an alien gladiator sport. Among her combatants is an alien champion played by…The Rock. To many fans, “Tsunkatse” was simply an attempt to cash in on the popularity of another UPN show, WWF Smackdown! (now WWE). The Rock even used his signature moves and eyebrow raising, to the delight of his alien crowd. Despite negative fan reaction, the episode was the highest rated of the season, and you can be sure that’s what the producers wanted.

Romantic tension between the Vulcan T’Pol and Commander Trip Tucker culminates in a “love scene” where T’Pol lets down her garment and displays her bare backside, including her naked rear end. Ten days before the episode aired, Janet Jackson had accidentally displayed her bare breast at the Super Bowl–surely factoring into the network’s decision to crop the scene and hide the bare bottom. The scene was shown without cuts in Canada and exists intact on the episode’s DVD.