If you are asking about the Latin Alphabet that we use today, there was no one person who can be identified historically who invented it. Other alphabets that are more recent, like the Cyrillic alphabet can be traced to a person or a few people who invented them. However, the Latin Alphabet is too ancient to be traced in this way.
The accepted history of our Latin Alphabet is that it originated with an unknown group of people in the Middle East who spoke a Semitic language. Because these people were in contact with others around the Mediterranean, they borrowed the idea of an alphabet from Egyptian hieroglyphics. They changed these hieroglyphics, though, to represent sounds instead of ideas.
The alphabet that they came up with was then adopted and changed by the Greeks. This happened a very long time ago, as early as the thirteenth century B.C., which is why there is no way to have any idea as to what individual or individuals came up with the specific letter shapes. From the Greeks, the alphabet was transmitted to the Romans. They changed it further, eventually coming up with 23 letters. The last three letters of our modern alphabet were added in the Middle Ages.
So, because the creation of the alphabet was a process and not a single invention, and because it happened so long ago, we cannot identify any one person or even a few individuals as the inventors or creators of our alphabet.