There are many to choose from, depending on your criteria:
1- Desert Eagle .50AE
2. .44 Magnum
3. 10mm
No
Unknown
A VERY good handgun- for most puposes. Durable, reliable, accurate, and powerful.
Probably, almost certainly, the .600 Nitro Express is the overall most power handgun bullet. Let me alter this answer by saying the .600 Nitro Express is a rifle round that one company made a pistol for. The most powerful handgun cartridge is the 500 S&W Magnum.
Not even close. There are several more powerful handgun cartridges, not counting the single shot pistols that use rifle cartridges. While Dirty Harry may have proclaimed it to be "The most powerful handgun in the world"- it is not.
There are many handgun rounds that exceed the 44 mag. 454, 460, 500 to name a few.
Can't be answered withou knowing if you are referring to a rimfire or centerfire 22
Fairly certain it is the Thompson Contender .600 Nitro Express for production firearms.
No, not by a longshot (no pun intended). Almost all "major" caliber handguns are more powerful than the 9mm.
Rifle, shotgun, or handgun? The 10 gauge shotgun at close range would be very high on the list, as would some of the buffalo rifle cartridges, such as the 45-110. The .45 Colt revolver was possibly the most powerful handgun of the day.
The .500 S&W magnum is the most powerful handgun round commercially available.
No. Most powerful handgun can be a bit ambiguous, considering that many short barreled rifles are sold in the US as handguns, minus the buttstock. As for purpose made and designed pistols, in the traditional sense, firing a dedicated handgun cartridge, the answer still is no. The most powerful production pistol in the world which fires a dedicated pistol cartridge is the Pfeifer Zeliska revolver. It fires a .600 Nitro cartridge. There are several other dedicated pistol cartridges which eclipse the .44 Magnum in terms of power - .454 Casull, .50 Action Express, and .500 Smith & Wesson Magnum are some of the better known ones. Even when Clint Eastwood claimed in the movie 'Dirty Harry' that the .44 was the most powerful handgun cartridge in the world (the movie was released in 1971), he was already outdated - the .454 Casull had already been introduced in 1959.