In one episode, Iznogoud actually manages to become the Caliph by changing bodies with him. However, due to his tyranny, he's overthrown by the people of Baghdad, who think that "everything's been worse since he threw the Grand Vizier in jail". After overthrowing him, the "Grand Vizier" (really the imprisoned Caliph in Iznogoud's body) becomes the new Caliph, thus restoring everything to normal (except the two now have swapped bodies and Iznogoud is in jail, together with Dilat Harat, who now has the body of the Caliph's food taster).
In Iznogoud Finally Caliph, a conspiracy is formed by the inhabitants of Bagdad to get rid of him. When asked who is in this conspiracy, Dilat replies to Iznogoud that everyone in Bagdad is, since except for the Caliph, they all hate him.
Arbitrary Scepticism: Played for laughs with Dilat, who outright says that while flying carpets and magicians are perfectly acceptable facts to him, a woman able to freeze people with her face is ridiculous.
Bad Luck Charm: One story revolves around the vizier obtaining a cursed diamond that brings very bad luck (your chair collapses, the doorknob snaps off in your hand, rooftiles fall on you in the middle of the desert) to the holder as a gift to the caliph. Of course, it's a Clingy MacGuffin, and things only get worse.
Narrator: Fortunately, there is a door. And fortunately, it is open. (next panel: sled crashes to the right of the door, Iznogoud cushioning for the Caliph) Narrator: Unfortunately, it's a little to the left.
Cerebus Syndrome: When the series were taken over by Tabary after Goscinny's death; while the stories remained mostly comical, they started having more coherent adventures with Iznogoud occasionally switching from Villain Protagonist to Anti-Hero.
Characterization Marches On: The Caliph's chambellan introduced in Iznogoud's Birthday was initially not specifically aggressive to Iznogoud and starts acting antagonistic toward him as a reaction to his angryness and obnoxiousness. When the same chambellan is reintroduced in later comics, he is portrayed as being basically Iznogoud's Arch-Enemy who is trying to protect the Caliph against his overthrowing attempts. Being jailed at the end of Iznogoud's Birthday didn't help as well (although Iznogoud had good reasons to do that, to be fair).
Devil in Plain Sight: Comically inverted; Iznogood looks, acts and IS evil, he actually possesses almost all the deffect requiered to be a villain, and people of Bagdad are perfectly aware of his desire to overthrow the Caliph... but the Caliph himself never suspects a thing, instead seeing Iznogoud as a devoted, good, trustworthy friend. He even once admitted he often received anonymous letters trying to warn him about it, but never believed them. Ironically, the Caliph is the only person Iznogoud bothers acting good with.
Eureka Moment: Evil characters also can have this, as Iznogoud proves:
Iznogoud: Do you have an idea how I could get rid of the Caliph, Wa'at Alaaf? Wa'at Alaaf: Sir, I'd rather feed my tongue to a cat! Iznogoud:(thinking) Tongue to a cat... the cat is a predator... the tiger is also a predator... the tiger is a man-eater... the Caliph is a man... so the tiger is a Caliph-eater!` Iznogoud:(loud) That's a great idea of you, organizing a tiger hunt! Wa'at Alaaf: A tiger hunt? Me? What?
"Freaky Friday" Flip: In an episode, a wizard invents a magic bowl: whenever two people drink consecutively from it, they exchange souls. Hilarity Ensues when this new invention gets tested by several patrons in an inn, just for fun. One of the catches is that it doesn't have to be actually people who drink: animals count too. (The wizard himself ends up in the body of a parrot.) Or even inanimate objects, for that matter.
Genre Savvy: Wa'at Alaaf, Iznogoud's henchman, has long since realised that Iznogoud will be Hoist by His Own Petard. One story has him going on a quest for an unknown item as soon as Iznogoud devises a plan for turning the Caliph into a statue; the item is revealed at the end to be a commemorative plaque in Iznogoud's memory, that Wa'at applies under the statue his master has become.
Good Is Dumb: The Caliph. He might be the nicest person on Earth, but God is he stupid.
In Les Cauchemars d'Iznogoud, he has a son named "Izveribad".
Heavy Sleeper: The Caliph spends much of his time contentedly asleep. His advisors know he's worried when he turns in his sleep more than twice a day.
Helping Granny Cross the Street: The Caliph encounters an old man who wants to get to the other side of the street. The Caliph helps him, then the old man wants to get back to the starting point because that's now the other side of the street.
He Went That Way: A variant. In one story, the evil vizier tries to use the cursed water of a swamp djinn to becom Caliph instead of the Caliph; anyone who touches the water disappears into it. Of course, while trying to get the water to the Caliph, more and more people (and a camel) touch or even drink the water, and Iznogoud keeps repeating the name of this trope when people wonder where they went. Finally, the Caliph's goldfish keeper tries putting his charge in the water, and when he wonders where the goldfish went... Actually, both Iznogoud and his henchman say this. While pointing in the opposite directions. Of course, this being Iznogoud, no one notices.
Human Chess: In one story, Iznogoud finds out that there is an island inhabited by two man-eating giants. He tricks the Caliph to come with him to the island, and they find out that the giants are vegetarians. Then Iznogoud asks the giants what they do to the people who come to the island. Guess what they do to them?
Hurricane of Puns: Iznogoud, by the same writer as Astérix, has an even higher pun-to-panel ratio, starting with the title of the comic (and main character). That's only the tip of the iceberg; the comic is full of puns in almost every page, which is often lampshaded by Iznogoud, who cannot stand them.
Identical Stranger: One of Iznogoud's many schemes involved using a merchant, who looked just like Caliph. In the end of the story, we see the partner of the merchant, and he looked exactly like Iznogoud.
Impossibly Compact Folding: In Iznogoud's Birthday, he opens a very small box and extracts a small piece of paper and proceeds to unfold it (it's so small that he needs a magnifying glass to start to unfold it). When completely unfold, the paper is several metres large. Of course, the box had been given to him by the guild of mages...
Ineffectual Sympathetic Villain: Iznogoud the Infamous, the ever-scheming but hapless Grand Vizier to the Caliph, who merely wants "to become Caliph instead of the Caliph."
Jerk With A Heart Of Jerk: at several points, Iznogoud saved Dilat from death or traps, only to then reveal he did this only because he needed him for specific purpose.
An extreme example in "Who Killed the Caliph ?", where Iznogoud shows up to save Dilat from execution and catch the Executionner trying to get Dilat paying him for mercy. Disgusted, Iznogoud states that mercy can't be bought and has to be given or received. He then notices a tortured prisonner, and orders him free, causing Dilat to believe he might have some mercy after all... then Iznogoud appoints the tortured new Executionner and orders him to torture the former one.
Kick the Son of a Bitch: The three Caliph's brothers that Iznogoud made disappear. While Troiround wasn't really developed enough to say if he was evil or not, Dheround was truly a bully that kept making deadly pranks to Iznogoud and mocking him for his small size and big nose. Katround was even worse, being a crazy man obsessed with making people disappear and attempting to literally erase Bagdad (including his well-intentioned older brother).
Legacy Vessel Naming: One story revolved around a sailor whose ship was named Shipwreck XXVII. Iznogound booked a cruise for the Caliph, who embarked on the Shipwreck XXVIII the next day.
Limited Wardrobe: Unless he makes a point of wearing a disguise, Iznogoud is always depicted in the same outfit.
Literal Genie: There is an episode with a genie which is summoned by rubbing a pair of slippers. He fulfills not only every wish, but every statement that the summoning character would pronounce. Hilarity Ensues, especially if the statement is a curse of surprise.
Magic Carpet: Such a common means of transportation that the Caliphate has an entire air force of 'em.
Iznogoud is a phonetic spelling of "is no good" in French.
Dilat Larat, i.e. "dilate la rate", refers to laughing uproariously in French — for an extremely Deadpan Snarker character.
The Caliph's brothers Dheround, Troiround and Katround translate to "Two-round", "Three-round" and "Four-round" respectively.
The Napoleon: Iznogoud is vertically challenged, and overcompensates with his ambition and bad temper.
Negative Continuity: Many, many stories end with Iznogoud seemingly irrevocably ruined, like being thrown into the dungeons, trapped in the far East, erased from existence or sent to another planet. It never stops him from trying again.
Noble Demon: Sultan Pulmankar is mostly known as a ruthless conquerer and a terrifying enemy, but he has a lot of rules (including always sparing his enemy's generals), is very affable to the Caliph when they are allied, and is shown to be a pretty good father.
Opposite Day: The animated adaptation did not feature an episode where Iznogoud attempted to take advantage of the Opposite Day to permanently take the Caliph's place.
Paper-Thin Disguise: Iznogoud's idea of disguising himself as a pumpkin seller is to carry a pumpkin around. And it works, too. It works so well his own guards won't let him back into the palace until he drops the pumpkin!
Pinball Zone: Extremely rare comic book example: one chapter has Iznogoud trapped in a pinball-machine wasteland.
Selective Enforcement: In a story, the eponymous evil vizir tries repeatedly to have the Calife commit a diplomatic faux-pas with the Sultan Pulmankar which would force him to either step down, resign his position or possibly even be killed on the spot by the outraged sultan. No matter what the vizir suggests, however, results in the Calife getting a cheerful, happy response for somehow following some bizarre and obscure tradition of his visiting guests. Then Iznogud says "drat" in response to the last one, which results in the sultan angrily taking offense to that word and demanding the vizir's life in slavery lest war be declared on the spot. The Calife gleefully agrees, insisting that "his good vizir would surely agree in the interest of peace." Gilligan Cut to Iznogud jailed and angrily trying to escape.
There was made a "The Returns of Iznogoud" album, which adds via Retcon epilogues to many of the "bad endings" of past stories, explaining how Iznogoud each time manages to return to normal status quo. With some exceptions. Some of these epilogues have him trying to escape the bad situation and ending in a worse situation. For example Iznogoud escapes the complex maze to end up in the inescapable dungeons. Iznogoud has been there before (in a much older story) but doesn't remember any way out. While there he meets an older incarnation of himself, still searching for the way out after all these years.
Stupid Evil: Iznogoud, while displaying intelligence occasionnally (and being much smarter than both most people around him and the Caliph) occasionnally falls in this trope: a lot of his plans backfire precisely because he made idiotic mistakes, or couldn't resist the temptation to Kick the Dog at the wrong time.
Surrounded by Idiots: Or, more often than not, by crazies. Special mention to the palace guards. Iznogoud even lampshades this several times:
Iznogoud: Can't we just fire all crazy people from this palace?! Dilat: Sure, boss, but who would be in charge of doing this?
Symbol Swearing: A story had him asking Dilat Larat for a rope, when he was down a cliff. Dilat dropped the entire length of rope. Iznogoud began cursing, with bombs, bones, axes etc. Then a lot of these items began falling from above, seemingly dropped by Dilat who thought Iznogoud was asking for them.
We Didn't Start The Führer: The comic has Hitler be an emissary of the Devil who was sent to our world to create destruction and terror.
Wretched Hive: Baghdad, especially from the Tabary era onwards, but already in the Goscinny era. Not only it's governed by the oblivious Caliph and the evil Iznogoud, but Humans Are Bastards in that city, and most citizens are hypocrites who complain all the time about Iznogoud's ruthlessness but are willing to help him for a few bucks, despite knowing the consequences if he's ever successful. In the story mentioned above where Iznogoud becomes the Caliph for a short time by changing bodies with him, after he starts unleashing his tyranny, one guy berates the wizard who helped him, but the latter doesn't seem to regret it.