The Pink Panther/WMG

Pink Panther takes place in the Known Space universe and Jacques Clouseau has the Teela Brown gene
Clouseau is The Ditz who succeeds by the power of crazy good luck. Remember that scene where all the world's top assassins are trying to kill him, and they all end up failing and getting killed due to unlikely coincidences (two of them go into stalls in a bathroom on opposite sides of the one Clouseau is in and end up shooting each other when he bends down, for instance), while Clouseau never even realizes what's happening? Does that not remind you strongly of Teela Brown in Ringworld, the woman who supposedly had genes that allowed her to somehow always have good luck? Clouseau having the Teela Brown gene would explain the things that happened in the movies very nicely. And Son of the Pink Panther makes this even more likely, as it indicates Clouseau was able to pass on his "style" genetically to his offspring. Of course, this would mean the Pink Panther series is probably set in the Known Space universe's past. Sure, it would have been before the Puppeteers started their breeding program for lucky humans, but the Teela Brown genes were presumably already in humanity before they started so it's not inconcievable that you could have had the occassional Teela Brown being born purely by accident.

Jacques Clouseau isn't really The Ditz we all think he is
He really is the competent, intelligent, badass detective that people who've never met him think he is in-universe. His ditzy persona is simply a ruse he maintains to cause his opponents to underestimate him. All the times it looked like he was saved by "good luck" he was actually perfectly aware of what was happening and what he was doing, and he was just careful to make it look as if he was oblivious and only survived by sheer luck. He's just so brilliant and badass he can outsmart and defeat world-class criminals and assassins while making it look as if he isn't even trying or is totally in over his head.

Jacques Clouseau is an Idiot Savant
Clouseau manages to do what he does because he's an idiot savant whose savant skill is dodging assassins. His lucky "accidental" escapes are actually his subconscious mind acting to save him. It spotted the sniper in the opposite building and made him sneeze the instant it saw the sniper get ready to pull the trigger, it knew those two guys were assassins so it made him go to the bathroom, lose the toilet paper, and duck to pick it up just as it sensed from the noises they were making that they were about to shoot, etc. Clouseau himself is not consciously aware of this, so he really does do things like defeat the world's top assassins without even realizing what's happening.

Steve Martin's Clouseau is an aged version of Alan Arkin's Clouseau.
Anyone who's seen the 1968 film "Inspector Clouseau", starring Alan Arkin, and Steve Martin's Clouseau in the recent reboot films knows their performances are very similar. If you want to pretend they all take place in a different reality than the Peter Sellers/Blake Edwards films than you could say that Arkin and Martin's Clouseau are one and the same.

Voodoo Man is an Eldritch Abomination
In the 1993-1995 Continuity Reboot, there is a Witch Doctor called Voodoo Man. However, his face is never shown on-screen, hidden behind a huge yellow mask. On the one occasion it almost got shown in the A Day in the Limelight episode "Voodoo Man", the reaction from the policeman character was one of shock and horror, suggesting his face is some sort of Eldritch Abomination. But this is an Epileptic Trees theory of course...

The 2006 reboot takes place in the same universe of that of the original films and the Clouseau played by Steve Martin is actually Jacques Gambrelli, Clouseau's son
And the Dreyfus played Kevin Kline is actually the original Dreyfus' (Herbert Lom) nephew, who coincidently is also called Charles.
 * When the movie was first announced in 2001, press releases did say that Steve Martin would be portraying an older version of Clouseau's son.

Clouseau never underwent Magic Plastic Surgery
Either Clouseau was kidnapped or killed and the people responsible for it hired Roger Moore to make the audience believe Clouseau changed his face.

Clouseau is God
Or at least God loves him that much, explaining why Clouseau survives the most deadly dangers in the world, everyday.

Dreyfus did not die at the end of Strikes Again
Several possibilities exist:
 * Clouseau traveled back in time to save Dreyfus.
 * Dreyfus did die and is replaced by a doppelganger.
 * Strikes Again is technically non-canon to the other films.
 * It was All Just a Dream from whoever's perspective it was.
 * Dreyfus re-materialized in his cell in the insane asylum from which he escaped.

The Ballon mansion was cursed, and the curse could only be broken when only one person remained.
For every time Clouseau came close to solving the mystery, another body was found. The explosion at the end ended the curse forever as Maria Gambrelli was all who survived.