Alfonse D. Pacelli was a Starfleet enlisted specialist (serial #GQ 882-101), a native of Mars, and the son of Helene and Salvatore Pacelli. He was born on stardate 40001.9 on Mars (Med file #UH-001-568), and graduated the Starfleet Technical Services Academy on stardate 40021.4. (TNG: "Eye of the Beholder")
On stardate 40299.5, he was serving at Utopia Planitia shipyards as a data flow management systems installation team leader, and was assigned to install and tune the starboard lower and portside mid-deck optical data nets of the USS Enterprise-D. (TNG: "Eye of the Beholder")
Pacelli was assigned to the Enterprise-D in 2365. (TNG: "The Child")
That is when he first started to appear as a non-speaking background character in TNG Season 2.
He was walking along a corridor when a non-corporeal lifeform, later known as Ian Troi, entered the ship in the form of a small, glowing sphere. (TNG: "The Child")
Pacelli was enjoying a drink in Ten Forward when Commander William T. Riker's father, Kyle Riker, came aboard the ship in 2365. (TNG: "The Icarus Factor")
He was on duty on the bridge, manning an aft station, when the ship was experiencing difficulties due to the influence of nanites and the bridge was flooded with nitrogen oxide. (TNG: "Evolution")
Pacelli worked at an aft console of the bridge when the Enterprise-D received a message from the Sheliak in early 2366. (TNG: "The Ensigns of Command")
Pacelli was having a drink in Ten Forward and later played a game of three-dimensional chess when the ship was investigating the Barzan wormhole. (TNG: "The Price")
He was also manning the conn when Rutian Ansata terrorists beamed onto the bridge and abducted Captain Jean-Luc Picard. Kyril Finn fired at his console. (TNG: "The High Ground")
In an alternate timeline created when the USS Enterprise-C traveled forward in time, Pacelli served on the Enterprise-D. He had a drink in Ten Forward. (TNG: "Yesterday's Enterprise")
A holographic duplicate of Pacelli was part of the illusion created by the alien Barash on Alpha Onias III in 2367. In this illusion he left the turbolift on the bridge and was passed by Captain Riker and Dr. Crusher. (TNG: "Future Imperfect")
Pacelli was on duty on the bridge when Admiral Norah Satie's aide Nellen Tore informed Captain Picard about his hearing in the interrogation room. (TNG: "The Drumhead")
He shared a drink with Nelson an other crewmembers in Ten Forward when Dr. Crusher told Deanna Troi about her feelings for Odan. (TNG: "The Host")
Just like the whole crew of the Enterprise-D, Pacelli was addicted to the Ktarian game in early 2368 and was seen playing the game at the bar in Ten Forward. (TNG: "The Game")
He also visited the bar while Berlinghoff Rasmussen had a drink there. (TNG: "A Matter of Time")
He attended the memorial service organized by Data for Geordi La Forge and Ro Laren when it seemed that they had died due to a transporter accident. (TNG: "The Next Phase")
Off duty, he had a date in Ten Forward and talked to his female companion while the Enterprise-D examined the murder on Relay Station 47. (TNG: "Aquiel")
Pacelli passed Doctor Beverly Crusher in a corridor shortly before Commander Riker gave her a friendly advice regarding her suspension and the death of Reyga and Jo'Bril. (TNG: "Suspicions")
By 2370, he had an average efficiency rating of 8.8 and was a specialist rating 6 in data flow management systems. On stardate 40116.5 he received the Tolley Citation for original thinking, and he received the Kliever Citation for systems design on stardate 40107.0. He also received the Kerrey Award for positronic field research on stardate 40096.2. On stardate 40127.8 he was assigned to the USS Philadelphia, and he was then assigned to the USS Syracuse on stardate 40276.2.
In 2370, Pacelli passed Counselor Deanna Troi and Ambassador Loquel in a corridor, moments before they met Eric Burton and his mother. (TNG: "Liaisons")
He was promoted to grade 4 non-commissioned officer on stardate 46992.5. (TNG: "Eye of the Beholder")
Pacelli was in attendance of a banquet held in Ten Forward when the ship was in orbit of Dorvan V. (TNG: "Journey's End")
He beamed down to Maranga IV, together with Diana Giddings, Russell, Armstrong, and other Enterprise-D crewmembers to attend the Kot'baval Festival. (TNG: "Firstborn")
Alfonse Pacelli was played by an unknown actor.
An okudagram readout of Pacelli's personnel file was displayed on a viewscreen that Deanna Troi was studying. Some of the facts could be called into question since she was involved in a very detailed hallucination when the data was shown.