Zombi is a series of European horror films that existed mainly as a cynical marketing tactic existing solely to cash in on an existing franchise's success that ended up ballooning into a strange naming ritual for obscure horror films that went right through until about the 80s. Every country has their own version of the Zombi series, making it really difficult to define due to how broad it is.
With Halloween on the way, let's look at this franchise and try to properly decipher it.
Zombi: The Italian Series
Zombi
This is Dawn Of The Dead. I don't mean that in the sense that Zombi is a rip-off or a remake. This movie is literally Dawn Of The Dead. In Italy, Dawn Of The Dead was released with the title Zombi after being re-edited by Italian horror-maestro Dario Argento and given a new score by the rock-band Goblin, who were responsible for the the iconic themes to many films such as Suspiria, Profondo Rosso and Tenebrae.
Zombi 2
Fun fact: Italian copyright laws dictate that it's perfectly okay to market a film as sequel to an existing property even when the two movies in question are unrelated. Italian cult horror director Lucio Fulci decided to make a sequel to Zombi released the very next year, with that sequel having nothing to do with Dawn Of The Dead.
This movie is about a caribbean island in which the dead are raised by voodoo magic, not really the biting contemporary satire that Dawn Of The Dead was. That's not to say it's a bad movie, because it's awesome. The gore effects are the perfect kind of over-the-top splatter that you'd expect in a film like this, and a zombie fights a shark. That's right, a zombie fights a fucking shark.
Zombi 3
Nine years later, Lucio Fulci directed a sequel to Zombi 2, this time about a viral outbreak revolving around a science project called Death One (which really could have only ended one way, couldn't it?). While it still maintained the great gore, the only really memorable part (to me at least) was the Warriors-style radio-jockey that exists solely to narrate the action and facilitate the ending scare.
Zombie Flesh Eaters: The British Series
Zombie Flesh Eaters
When Zombi 2 was released in the UK, it was under the title Zombie Flesh Eaters, disregarding any possible relation to Dawn Of The Dead. It was originally on the British Film Classification Board's list of 'video nasties', requiring one minute and forty seconds before granting the movie an X-rating. However, as of 2005, the movie has been released uncut.
Zombie Flesh Eaters 2
This is actually Zombi 3, as you can tell because they have exactly the same poster. This movie was re-released in 2015 with a reversible cover letting you choose between calling this Zombie Flesh Eaters 2 or Zombi 3. Come to think of it, isn't the title Zombie Flesh Eaters a little redundant? It's like calling Ocean's Eleven 'Thief Item Stealers' or calling James Bond 'Spy Women Banger'.
Anyway, I'm getting side-tracked.
Zombie Flesh Eaters 3
This was originally an Italian movie called Oltre La Morte or After Death, being released in 2002 with the title Zombie Flesh Eaters 3. The story sounds a little familiar, involving zombies brought to life by voodoo magic and rampaging on an island.
Zombie: The German Series
Zombie
In Germany, Dawn Of The Dead was released under the title Zombie (Getting straight to the point. Gotta love that German efficiency). It received the same shorter cut that the Italians did courtesy of Dario Argento.
Zombie 2: Das Letzte Kapitel
Unlike the Italians, who tried to make their own sequel to Dawn Of The Dead, the Germans released the actual sequel; Day Of The Dead as the sequel to Zombie. As for Zombi 2, that was released in Germany under the title Woodoo, completely unrelated to this series. This, however, was a trend that would not continue.
Zombie III
Zombi 3 (or Zombie Flesh Eaters 2) was released in Germany under the title Zombie III. There's not really much else to say about that...
Zombie Flesh Eaters: The Thai Series
I'm going to save you guys a little time and point out that, for the most part, the Zombi series in Thailand is basically the same as the Zombie Flesh Eaters series from the UK.
Zombie Flesh Eaters
Zombie Flesh Eaters 2
Zombie Flesh Eaters 3
Zombie Flesh Eaters 4
This was originally a film titled Uccelli Assassini or Killing Birds. Fun fact: This movie has barely anything to do with zombies and/or killer birds.
Zombi: The American Series
Here's where things get a little (more) confusing...
Zombie
Obviously, the Americans didn't feel obligated to connect Zombi 2 to Dawn Of The Dead, as that was already part of its own lucrative franchise, so they just gave that movie the title of Zombie.
Zombie 3
But wait, where's Zombie 2? Welcome to the Zombie series, bitch. Zombi 2 was released under the name Zombie 3 in a three-part DVD pack with the following two movies.
Zombie 4: After Death
What the UK would call Zombie Flesh Eaters 3 would be what the US call Zombie 4: After Death, which is a title closer to the Italian release.
Zombie 5: Killing Birds
Well, there you go. The American Zombie series ended with the same movie that the Thai series did; Killing Birds.
But the story doesn't end there...
The Alternate US Zombie Series
Zombie
Obviously the series started with Zombi 2 released under an alternate title. However, this iteration of the series would take a different turn.
Zombie 2
Yep, same movie, different title. Imagine how annoying it would be to try to add this movie to your collection only to discover that it was the same movie.
Zombie 3: Return Of The Zombies
This was an Italian movie titled La Orga De Los Muertos (Orgy Of The Dead) although its alternate titles in the US were The Hanging Woman, Beyond the Living Dead and Terror of the Living Dead (your guess is as good as mine).
It involves a mad scientist who raises the dead with the help of his necrophiliac grave robber friend. Moving on.
Zombie 4: A Virgin Among The Living Dead
This was original a Spanish-French erotic-horror film titled Christina, Princesse de l'rotisme in which they actually added footage of zombies to the film in order to release it as a zombie film, much to the chagrin of the director. It's actually a movie about a woman who discovers that her estranged family are all ghosts that haunt their previous residence.
Zombie 5: Revenge in the House of Usher
This isn't even a zombie movie. It's more of a supernatural, psychological gothic horror movie, in which a disturbed man believes a house to be attacking him, with the title Revenge in the House of Usher.
Zombie 6: Monster Hunter
This isn't a movie about hunting monsters. It's not even a zombie movie. It was originally a movie titled Absurd, about a greek invincible cannibal. It was pretty much a pseudo-sequel to a film called Anthropophagus. Speaking of which...
Zombie 7: Anthropophagus
Oh come on!
Leftover Zombi Movies
Zombi 3: Da Dove Vieni?
This one's a Spanish-Italian zombie-film that was originally titled No Profanar El Sueo De Los Muertos or Let Sleeping Corpses Lie. Other titles include The Living Dead at Manchester Morgue and Don't Open the Window (which is funny, considering that this movie was the inspiration for Edgar Wright's Grindhouse trailer called Don't).
Zombie 3
This movie was originally called Zombie Holocaust and Zombi Holocaust before being released as Zombie 3. It involves zombie attacks on an island (familiar motif, eh?) but with the added bonus of a tribe of cannibals that fight the zombies. Hell yeah.
Zombi 3
Nightmare City is a classic zombie exploitation movie also known as City of the Living Dead and Incubo Sulla Citt Contaminata. It stars Hugo Stiglitz and it's known mainly for its kick-ass theme music and its bat-shit crazy ending. Also, Tom Savini is directing the remake. It was also released with the Zombi 3 title at some point.
Zombie 3
This one's an Italian Grindhouse zombie movie that was originally known as Le Notti Del Terrore before being released in English speaking countries with names like Burial Ground, Nights of Terror, Zombi Horror and The Zombie Dead. It would also get the Zombie 3 title.
Zombi 4
The Greeks were the ones that bestowed the title of Zombi 4 on this Spanish-Italian horror film in which a scientist turns himself into a monster with a deadly bacteria before going on a rampage.
Zombi 7
This is pretty much a fan-film from the director/writer of the Violent Shit series, whose repertoire is entirely shlocky, trashy, straight-to-video exploitation. It originally had the incredibly cumbersome titles of Zombie '90: Extreme Pestilence and Zombie 2001: Battle Royale. This guy also directed a remake of Anthropophagus titled Anthropophagus 2000.
So, that's the Zombi series in all its complicated glory.