Intruder alert was an alert status on Federation starships and space stations. It could be declared at any time, by any member of the crew upon sighting an intruder on board. It could also be activated automatically based on predefined criteria, such as entering a restricted area. The alert was announced by audio and crewmembers were expected to take appropriate action.
In 2369, Miles O'Brien activated the intruder alert and called a security team into his quarters when the fictional character Rumpelstiltskin appeared in Molly's bedroom. (DS9: "If Wishes Were Horses")
In 2371, when the energy patterns of the Komar and Chakotay were forcing the crew of the USS Voyager to perform actions against their will, Kathryn Janeway initiated an intruder alert. (VOY: "Cathexis")
In an alternate timeline, Neelix helped repair the internal sensors aboard the USS Voyager after they had been seriously damaged due to repeated Krenim attack. He wanted to try several variations on the audio warning, but security chief Tuvok ordered him to keep the standard alert. (VOY: "Year of Hell")
Tuvok initiated an intruder alert and called for security to deck one when the two astronauts from the planet that Voyager was trapped above in orbit transitioned into Voyager's timeframe. (VOY: "Blink of an Eye")
|Colored alerts:||Red • Double Red • Yellow • Blue • Gray|
|General alerts:||Battle stations • "Brace for impact" • General quarters|
|Battle • Evacuation • Fire • Intruder • Perimeter • Proximity • Security • Standby • Tactical|