(covers information from several alternate timelines)
A forged holographic recording
Forgery was the act of creating a false thing. Such a thing was called a fake, a forgery, or a phony. One creating such a thing was called a forger.
In 2259 of the alternate reality, Carol Marcus forged her transfer to the USS Enterprise under the alias "Carol Wallace" to determine what was inside the advanced long-range torpedoes, a fact she admitted to James T. Kirk while preparing to open one up. (Star Trek Into Darkness)
In 2270, Spock described the fake communicators Ari bn Bem had provided him and James T. Kirk with as "excellent, but non-working forgeries". (TAS: "Bem")
In 2293, Spock suggested that somebody must have forged an entry in the USS Enterprise-A's data banks as all the photon torpedoes supposedly fired at Kronos One were still present. (Star Trek VI: The Undiscovered Country)
In 2369, while playing Sherlock Holmes on the holodeck, Data accused a suspect of forging his brother's handwriting on a suicide note. (TNG: "Ship In A Bottle")
Also that year, Kira Nerys was certain that Gul Darhe'el's death certificate was forged. (DS9: "Duet")
In 2374, Captain Benjamin Sisko and Elim Garak created a forgery of a supposed Dominion meeting outlining a plan to invade Romulus, placed on an optolythic data rod. It was correctly deduced as a fake by Romulan Senator Vreenak, who promised to expose the deception to the entire Alpha Quadrant. However, he was killed by a bomb placed on his shuttle by Garak and carefully staged to make it appear the attack was caused by the Dominion. Furthermore, the rod was discovered in the remains and the imperfections that would have exposed it as a forgery dismissed as damage caused by the explosion. (DS9: "In the Pale Moonlight")
In 2375, Odo wondered if Ensign Nog's orders to remain on medical leave were forged. (DS9: "It's Only a Paper Moon")