I’m not so far into Star Wars that I actually know who most of the extended universe characters are. I thought it would be interesting to look up each one of these guys in Wookiepedia to figure out who they are. Starting with Astromechs, I actually learn that many of them are from the movies.
R2 Astromech:
The R2-series astromech droid was a model of astromech droid produced by Industrial Automaton, boasting a level of success that was never equaled in Industrial Automaton's long history. A combination of excellent design, high-quality marketing, and good timing made this astromech droid one of the most sought after droids in history, and one of the few vintage astromech series still in active production decades after it was first designed, including the prototype R2-0. The line was so successful that the Galactic Empire would later take credit for the design. The average cost for an R2 unit was about 4245 Republic Credits.
R2-D2 (Episodes I-VI):
Really? Watch the movies.
R2-D6 (The Force Unleashed novel):
In 1 BBY, R2-D6 served onboard the Y-wing of Rebel pilot Wedge Antilles during the Battle of Kamino. During the fighting, Deesix was used as a handhold by Starkiller, a clone of Galen Marek who was attempting to infiltrate the cloning facilities on the planet in order to rescue Rebel fighter Juno Eclipse. Although nervous about the escalating conflict, Deesix nevertheless stayed true to the current mission and survived the battle.
Deesix was later assigned to a Y-wing on recon duty in the Muugrah system searching for a pirate base. Though the Y-wing did find the base, it was soon attacked by the pirates and the pilot was forced to eject. Deesix became trapped in his socket due to the damage dealt to the ship, and played dead as the Y-wing was tractored aboard a pirate ship, which proceeded to take it to a nearby pirate outpost. Once the outpost commander saw what his men had brought in, he panicked and ordered the fighter disposed of lest he be linked with the Rebel Alliance. The fighter, with Deesix still aboard, was loaded into a cargo container and dumped in Squarn's Junkyard on the planet Muugrah.
Rewiring his socket to draw power from the Y-wing, Deesix was detemined to return to the Alliance with the information he had gathered, and was keen to regroup with the crew of the fighter. He was eventually discovered by a group of Rebels who were looking for spare parts to fix their hyperdrive. They managed to free Deesix from his socket with the help of a repulsorlift skiff, which they had repurposed as a VTOL vehicle. Deesix insisted on accompanying them with their searches. While the group continued their search, however, they were attacked by the same group of pirates who had previously sent Deesix to the junkyard, operating on orders to retrieve the droid for Imperial Intelligence. The fight ended with the Rebels victorious thanks to the help of Squarn's mercenary forces, and they soon left the world with Deesix in tow.
Once Deesix was delivered to a Rebel base, the information in his memory was downloaded, saving many Rebel lives from the pirate attacks.
R2-F2 (none)
He was created for the game. No other mention of him exists.
R3-A2 (Episodes V)
R3-A2 was an orange R3-series astromech droid. It was seen in the Rebel base during the Battle of Hoth in 3 ABY.
Like other R3 droids manufactured by Industrial Automaton, R3-A2 was designed for high tech work on military installations. The clear plastex dome shows off a newly-updated Intellex V computer system, which contained detailed statistics on thousands of military starships. R3-A2 could hold up to 5 hyperspace jumps in active memory, and could also coordinate piloting coordinates and approach angles during combat. His eye was a round kind unlike most R3 units.
R4-D6 (Episode IV)
R4-D6 was an R4-series agromech droid, which was primarily colored navy blue, belonging to the Rebel Alliance at its base on Yavin 4 in the year 0 BBY.
R5 Astromech (Episodes I-II, and lots of comics, tv shows, games, etc):
"A meter-tall stack of the worst business decisions you could possibly want."
―Mechtech Illustrated, criticizing the R5-series
The R5-series astromech droid was a line of low cost astromech droids built by Industrial Automaton. Based upon the success of prior astromech models, such as the wildly popular R2-series, Industrial Automaton intended the R5-series to cater to budget buyers at the cost of some functionality.
R5-D8 (Episode IV)
R5-D8 was an astromech droid used by Jek Tono Porkins during the Battle of Yavin. He had used the droid since he was a part of the Tierfon Yellow Aces. R5-D8 exploded together with Porkins's X-wing during the assault on Death Star I.
R5-K6 (Episode IV):
R5-K6 was an R5-series astromech droid that was built by Industrial Automaton and belonged to Garven Dreis, the leader of the Rebel Alliance's Red Squadron, an elite X-wing starfighter squadron that participated in the assault on the first Death Star at the Battle of Yavin. R5-K6 previously served at the Dantooine Rebel base. He was destroyed along with Dreis's X-wing when it was shot down by Darth Vader.
R5-P9 (Episode VI):
R5-P9 was the black and gray astromech droid that served onboard Ekelarc Yong's Y-wing starfighter during the Battle of Endor. The droid was destroyed, along with Yong and his fighter during the battle.
R7-T1 (Before the Storm novel)
R7-T1 was an R7-series astromech droid that was produced by Industrial Automaton some time after the Battle of Endor.
R7-T1, nicknamed Artee, served as Luke Skywalker's in-flight astromech droid when the Jedi Master borrowed an E-wing escort starfighter from the New Republic Defense Force for a brief time during the Black Fleet Crisis. However, Skywalker never became comfortable with either the new starfighter design or the newer-model droid, and soon abandoned them in favor of his usual T-65 X-wing starfighter and his old friend and trusty astromech droid, R2-D2.
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What did I learn? Well, R2-D6 has had some crazy adventures on his own and I understand how he gives the Elite Pilot skill to his pilots. I also found R5-D8 interesting since he is Porkin’s droid. It makes me think about putting him on Porkins and it actually makes sense. R5-K6 sounds pretty boring overall, but thinking about putting him on Garven Dreis makes a lot more sense. Garven wants to spend his actions on Focus and hopefully he just needs to Target Lock on something once. Makes more sense now.
Now to look at some of the other guys....