There are a lot of black Optimus Primes out there, and a lot of their stories overlap.
- The first was Scourge, from the 2001 Robots in Disguise continuity. Originally an Autobot protoform, he and his five teammates were stolen by Megatron, who had them scan Earth modes and injected each of them with a bit of his own evil Spark to turn them against their former comrades. While the sixth protoform was scanning a tanker truck, Optimus Prime jumped in to save the driver, meaning he was part of the scanning process, too. Embarrassed by his origins, he seeks nothing more than the utter destruction of Optimus Prime, believing that will free him from the Autobot leader's shadow.
- The next was the original Nemesis Prime, from the 2003 Universe line. An alternate reality's Optimus Prime was a bloodthirsty warrior - even moreso than Micahel Bay's Optimus! He was defeated by an even eviler Megazarak, who was jumping between dimensions. His body was left to decay in Cybertron's Rust Sea, but Unicron became aware of the body, cloned it, and then tortured the clone until it became his willing slave. He carries the Dead Matrix, which can destroy Primus, just as the regular Matrix can destroy Unicron.
After attempting to destroy Primus and being defeated, Nemesis Prime 1 was recruited by The Alternity, a group of highly advanced Transformers from the distant future. His experiences with them healed his broken mind and saw him embrace his heroic legacy. He changed his name to Black Convoy.
- Nemesis Prime 2 also came out in 2003, in the Armada line. He only existed on a strange planet on the other side of a black hole. He was barely more than a beast in Optimus Prime's shape, and when he was defeated, he crumbled into dust, with his entire planet soon following suit. In a separate tie-in comic, he was shown to be travelling to multiple worlds, ravaging them ("scourging" them, you might say) and harvesting the negative psychic energy this created to charge something called the "Doomstone."
2004 brought Grand Scourge, who was possibly an upgraded version of Nemesis Prime 2 (who had been called Scourge in Japan). He worked for Unicron as his "Matrix Hunter," charged with travelling between dimensions to find and kill any Optimus Primes he could.
- Nemesis Prime 3 was introduced in 2006 as part of the Alternators line. He was built by humans, based on a scan of Optimus Prime's programming, but they still needed a power source for him: scanning subspace for anything powerful enough, they accidentally tapped into the dimension that serves as Unicron's power battery, and specifically a fragment of Nemesis Prime 1's Spark, making NP 1 and 3 almost like stepbrothers.
- Nemesis Prime 4 was in the 2007 Classics portion of the G1 continuity. This one was an unknown grunt who was put through extensive rebuilding and brainwashing by Straxus. Exactly what Straxus' goal with this was is unknown, because he died, and his creation now lurks in the most dangerous parts of Cybertron, a threat to everybody.
- Nemesis Prime 5 is from the Animated continuity. He was part of the same program of copying Autobot shells that created Toxitron and the Stunicons. Once he was completed, though, he was quickly spirited away by his reality's Starxus.
- Nemesis Prime 6 appeared in the Transformers Prime series in 2012. There, he - or rather, "it" - was a remote-piloted drone built by the human group M.E.C.H., which uses cutting edge technology to try to take over the government. Tired of being opposed by the Autobots, they tried to frame Optimus Prime with their fake robot.
After that, their stories start to get very same-y, with a few minor changes:
- 2013: Masterpiece Nemesis Prime 7 - clone created by Unicron
- 2013: TFCC Scourge - clone created by Jhiaxus
- 2013: Transformers Go! Hunter Nemesis Prime 8 - evil version of Prime from another dimension
- 2014: Generations Nemesis Prime 9 - clone of unknown origin who serves Unicron
- 2014: Age of Extinction Nemesis Prime 10 - human-built copy whose only friend is Nemesis Grimlock
- 2015: Robots in Disguise Nemesis Prime 11 - a duplicate built by Knockout because he thought the Autobots would have fighting someone who looked like their leader
- 2016: Earth Wars Nemesis Prime 12 - clone created by Shockwave
- 2018: Power of the Primes Nemesis Pax and Nemesis Prime 13 - clone
- 2020: War for Cybertron Trilogy Nemesis Prime 14 - Unicron-resurrected body of Optimus Prime, sent back in time from the future
- 2022: Legacy Scourge - wants to have zoom zoom fun fast times
That's not every black copy of Optimus Prime there's ever been, but it is all the ones who have actually been declared separate characters, rather than just being Optimus with a different shirt on.