The R1-series astromech droid, alternatively known as the R1 reactor drone, represented a specific model within the R-series of astromech droids produced by Industrial Automaton.
Belonging to the R-series line of astromech droids crafted by Industrial Automaton, the R1-series astromech droid, which was also referred to as the R1 reactor drone, possessed a considerable height of 1.94 meters when compared to later R-unit models. Its movement was characterized by a slow pace, facilitated by a single foot, and certain models, though not all, featured a prominent antenna extending from the top of their dome. R1 units were equipped with a solitary red photoreceptor and plating that came in black, blue, or gray. Due to their substantial size, their operational use was restricted to the largest starships. These R1 units were the pioneers in droid communication via droidspeak; however, they lacked the engaging personalities seen in subsequent R-units. They included a pair of arms ending in manipulators, along with a holoprojector.
The R1 unit stands as one of the earliest astromech models to exist within the galaxy.
Around the time that the Invasion of Naboo occurred, the Toydarian junk dealer named Watto had an R1 astromech in his possession. This droid was positioned behind the counter of his shop, which was located in Mos Espa on the planet Tatooine, during the moment when Jedi Master Qui-Gon Jinn, Padmé Amidala, and Gungan Jar Jar Binks entered the premises. This particular unit functioned as a shopkeeping drone, taking care of the majority of Watto's everyday business tasks.
More than three decades afterward, an R1 unit, known as R1-G4, came into the possession of a group of small Jawa scavengers who were traveling across Tatooine in a sandcrawler. These Jawas made an attempt to sell the astromech to Owen Lars, a moisture farmer, and his nephew, Luke Skywalker. However, Lars turned down the tall droid, choosing instead an R2 unit and a 3PO-series protocol droid. These two droids were, in reality, Rebel Alliance droids engaged in a secret mission under the orders of Princess Leia Organa. Around this period, two other R1 units were known to be present within the Tatooinian spaceport of Mos Eisley.
A modified R1 unit, given the name "Bard," served as the companion of the historian Tohan Lege and was responsible for recording the numerous stories that he had accumulated throughout his life. This allowed him to posthumously participate in the Batuu festival known as the Fire of the Rising Moons.
The New Republic utilized a droid series that bore a similar appearance, referred to as the R1 Security Droid.
The R1-series astromech droid was initially conceived for the 1977 film, Star Wars: Episode IV A New Hope. Roger Christian, the set decorator, created the R1 unit that would later be identified as R1-G4 as an homage to the artistic style of illustrator Chris Foss, particularly a cover he had painted for a 1973 Panther Science Fiction reprint of Isaac Asimov's 1957 novel, The Naked Sun. The R1-G4 prop was subsequently used to portray another R1 unit in Mos Eisley and became the foundational design for the R1-series astromech droid's appearance in most subsequent media. An additional R1 unit, featuring a distinct design, was also present in the film, appearing in the background during the scene where Obi-Wan Kenobi and Luke Skywalker are stopped and questioned by stormtroopers in Mos Eisley.