Eli Hollander

From Memory Alpha, the free Star Trek reference.

Eli Hollander was a holographic character in a holoprogram set within the Ancient West town of Deadwood, which Alexander Rozhenko created for himself and his father, Worf, in 2369. Known as "the Butcher of Boseman" [sic], he was the meanest, toughest, and fastest gunslinger in the West. At the time, there was a $5,000 reward for Hollander, "Wanted Dead or Alive", for the brutal murder of 19 men and 4 women in Boseman, Montana. His father, Frank Hollander, was equally dangerous.

After a skirmish in a bar, Eli was arrested by Worf, posing as the town sheriff. While imprisoned, Eli vowed to Worf that his father would free him; Worf, however, believed there was little threat as they were only imaginary characters.

However, due to a malfunction caused by an experiment that Geordi La Forge and Data were conducting in Engineering, the program's safety protocols were shut off, and many of the holographic characters, including Eli and his father, took the image and physical capacities of Data – giving them the strength and speed of an android. When Eli's father abducted Alexander, Worf was forced to turn over Eli in exchange for his own son. Knowing that a gunfight was sure to erupt and that the holodeck's safety protocols were no longer engaged, Worf rigged a protective force field with his combadge. When the exchange was made, a shootout commenced and Worf was able to deflect Frank's bullets long enough to disarm him and his gang. He then told both Frank and Eli to "never show your face in this town again." (TNG: "A Fistful of Datas")

Eli was played by John Pyper-Ferguson and Brent Spiner.