(covers information from several alternate timelines)
Lieutenant Joseph "Joe" Carey was a 24th century Human Starfleet officer. He served as assistant chief engineer on board USS Voyager during its seven-year journey through the Delta Quadrant. He had a wife and two sons. (VOY: "Parallax", "Prime Factors", "State of Flux", "Friendship One")
After the death of his department head upon Voyager's violent transfer to the Delta Quadrant, Carey became the acting chief engineer. (VOY: "Caretaker") As such, he was Captain Kathryn Janeway's natural selection as the new permanent chief engineer. However, former Maquis member B'Elanna Torres was suggested for the position by Commander Chakotay, as he believed her to be the better engineer. The suggestion was, at first, improbable and turned down by Captain Janeway, who did not believe Lieutenant Torres' behavior to be exemplary and worthy of such a position.
In a recent disagreement, Carey had been struck by Torres even though he was, at that time, her nominal superior officer. The blow had broken Carey's nose in three places and had narrowly missed causing him brain damage. For a time, tensions between the two were predictably high. While both were under consideration for the job of chief engineer, however, Carey was forced to recognize Torres' superior engineering expertise. After Torres was chosen over him for the position, they quickly made a genuine effort at reconciliation. (VOY: "Parallax") Within a short period of time, he indicated he had been working hard to make himself a valuable member of Lieutenant Torres' team, while she, in return, had issued no complaints about his performance. When he was considered a suspect in covertly contacting the Kazon-Nistrim, as his engineering station was the point of a secret transmission during a systems analysis, Chakotay pointed out that he did have opportunity and motive – being looked over for promotion – Janeway made a point of stating that "[h]e's also had a distinguished Starfleet career." (VOY: "State of Flux")
Several months after being stranded in the Delta Quadrant aboard Voyager, Carey – along with Torres and Seska – conspired to trade a downloaded Federation library of literature to the Sikarians, in exchange for a folded-space transporter that the Sikarians called the "spatial trajector". The officers' plan was uncovered by Tuvok, who made the exchange himself, in defiance of Captain Janeway's orders. The Sikarian technology ultimately proved incompatible with Federation systems, though this proved less important than Carey discovering that the quartz mantle of Sikaris was a focusing method crucial to the system's function. (VOY: "Prime Factors")
Later in 2371 – while on a scouting expedition with Commander Chakotay and an away team – Carey discovered a type of delicious-looking apple and happily announced that there were trees filled with them over a nearby ridge. However, Neelix pointed out that the apples (called Kaylos) were extremely poisonous. Tuvok discovered, later that day, that someone on board Voyager had secretly given Starfleet technology to the Kazon. To hide her tracks, Seska tried to frame Lieutenant Carey. He was confined to quarters during the investigation, until after he was cleared of the accusations. (VOY: "State of Flux")
In 2378, Carey was part of an away team that visited an unidentified planet in Grid 310, which was irradiated with antimatter radiation, searching for fragments from the Friendship 1 probe. The people's then-leader Verin took the Voyager away team hostage, demanding that Captain Janeway should relocate her people to another planet. Janeway first suggested, though – as a sign of good will – that Verin should return one of the hostages in exchange for food and medical supplies. Verin agreed to this exchange and told Carey to set up his transport enhancers, so he could be beamed back to Voyager. However, seconds before Carey's transport, Verin shot him with an antimatter weapon. Carey was beamed back to Voyager but arrived in sickbay dead, having been shot through the heart. After his death, it was discovered he had been building a "ship in a bottle" model of Voyager. The miniature was mostly completed, with only one nacelle left unfinished. (VOY: "Friendship One")
Alternate realities and timelines
In an alternate timeline wherein Voyager was still in drydock, Carey was working in engineering when he met Seven of Nine, who had been sent back in time by Captain Braxton. Carey tried to engage her in small talk – interested in becoming acquainted with the new crew and saying the two of them should have lunch together sometime – but Seven excused herself, stating she was temporarily assigned to Voyager from Utopia Planitia. Later, while Captain Janeway and Admiral Patterson were conducting an initial tour of Engineering, a malfunction crept up in the EPS conduits. Carey planned to run a diagnostic on those systems that morning and offered to fix the malfunction, but Janeway noted that she wanted an opportunity to get her hands dirty. (VOY: "Relativity")
Carey was played by Josh Clark. Clark had previously played an unnamed tactical ensign in TNG: "Justice". Even though the two roles were many years apart, Clark is very recognizable, so it seems as though Carey may have served on the Enterprise-D earlier in his career.
In the first draft script of "Caretaker", Carey was described as "an Ensign in his thirties". In the final draft of the teleplay, this description was instead changed to "a Lieutenant in his thirties".
Carey's precise position on Torres' team was never explicitly defined. While presumably he remained the assistant chief engineer, Carey's virtual disappearance after the first season of Star Trek: Voyager might suggest otherwise. Indeed, if he remained Torres' assistant, it is somewhat curious that he was not present at some of the more major accomplishments of the engineering section, such as the debut of the quantum slipstream drive. However, he may have just as likely been assigned by Torres to head the department when she was off-duty.
Following his first season appearances, Carey was primarily used in time travel and alternate timeline stories which needed to imply the past. "Friendship One" was his only appearance in the "real", post-season-one timeline.
In the Voyager short story "The Ones Left Behind", Joseph M. Carey lived with his family in Cobh, County Cork, Ireland on Earth by 2371. The same year, he turned down a position on the USS Enterprise-D, in order to transfer to the Voyager to serve as the ship's assistant chief engineer. His wife is named Anne Carey and his sons are named JJ and Patrick.
In the short story "Letting Go", Carey's wife is named Abhaya Parekh and his sons are named Devraj and Michael.
In the video game Star Trek: Starship Creator, Carey's wife is named Dina Carey and his sons are called John and Josh. Carey was born on Danula II. He previously served on the USS Ulysses, the USS Deneva and the USS Sutherland.