The Borg Class 4 tactical vessel was a type of heavily-armed Borg cube utilized by the Borg Collective. The tactical cube differed from the standard Borg cube in several ways, the most notable being the extensive hull armor that covered a large portion of the exterior hull of the ship. The interior was also slightly altered from what is known of Borg "architecture". The vessel's central plexus was protected by multi-regenerative security fields.
Only one such vessel was observed by Starfleet – by the USS Voyager in 2376. The tactical cube was caused to self-destruct by the Borg Queen during a brief civil war within the Collective. (VOY: "Unimatrix Zero", "Unimatrix Zero, Part II")
Ships of the class
- The Borg tactical cube was also used in the climactic final level of Star Trek: Legacy. Oddly, creators of the game boasted in a video interview that the vessel was of their creation, and that it had been designed especially for the game's finale. This is highly unlikely, as, not only had it clearly first appeared on Star Trek Voyager two years before, but Doug Drexler's name was not mentioned at all during the interview in question. Also, when the vessel appeared during the mission, Admiral Janeway says she had encountered such a vessel before, and had help destroying it, clearly referencing the events of the episode.
- Tactical cubes are also featured in Star Trek: Armada II, in which eight of them can combine to form a massive tactical fusion cube.
- Ships of this class also feature in Star Trek: Conquest; however, the ship is ranked as a "cruiser" and has inferior fire power and shielding to an average cube.
- Tactical cubes are found in several campaign missions of Star Trek Online, classified as a dreadnought. Each one has approximately two times the weaponry of a standard cube and roughly four times the hit points, requiring a small fleet to destroy.