Walther PP
Felix Leech and his Walther PP
Hippocrates Noah and his Walther PPK (right hand)
The Walther PP (German for Polizeipistole, literally "police pistol") was a semi-automatic pistol used on Earth by civilians and the police.
In the Dixon Hill series of holographic programs, Felix Leech, a hit man for Cyrus Redblock, owned a stainless steel Walther PP with pearl grips. This weapon was fired by Leech, wounding Whalen in the process. (TNG: "The Big Goodbye")
In the holoprogram Julian Bashir, Secret Agent, the scientist Doctor Hippocrates Noah and the secret agent Julian Bashir were armed with the Walther PPK, a variant of the Walther PP. Dr. Noah's gun was nickel-plated and Bashir's gun was one of many hand-held weapons he kept stored, ready for use, in his apartment's armory. (DS9: "Our Man Bashir")