In the Nickstaverse, there are several alien races known to Earth. Unfortunately, First Contact didn't happen under the best terms.
In the year the Gregorian calendar calls 2003 AD, the Jhinu, a race of blue, tentacled humanoids capable of evolving on command, discovered faster-than-light travel. Unfortunately, the world government of Jhin subscribed to "we're the fittest and no one else will survive". Fearing a galactic genocide, the underground resistance had to act fast. Luckily, the Jhinu government had one major flaw: hubris.
The resistance was able to sneak pilot Atering Vuvusol past prideful guards no problem, and was able to take to the stars to warn planets of the impending Jhinu invasion. He managed to warn seven races before his ship ultimately crashed.
The Odrugarans, a race of long-necked, white bureaucrats
The Keedonzians, a race of blue humanoids with deafening sonic screams
The Qularr, a race of pink insectoid geneticists
The Kalishari, a race of color-changing humanoids that can inflate like balloons
The Toractans, a race of super strong, large, gray humanoids
The Fex, a race of blue, methane-breathing felinoids
The Terrans, a veritable slew of 50 different species (but mostly humans)
Shortly after introducing the Terrans to FTL, Vuvusol received word that the Jhinu had begun their master plan, starting with a race called the Hzeel. It was then that the original seven races started putting out messages for other species to join the fight. Not only did the Hzeel put up a lot of resistance, but the Fex came to their aid, risking life, limb, and asphyxiation on an oxygen-based atmosphere.
Other races soon followed suit in recruiting races to help. The Kalishari recruited the Jakkari and Mon'dabi. The Toractans recruited the Harkarthians and Mandaarians. But the Terrans were the most prolific, recruiting the Kadathari, Osathri, Roin'esh, and Varanyi.
The war raged on for two years until 2005, when the Jhinu attacked a vessel they thought was filled with Terrans, only to discover they actually attacked a vessel full of similar-looking Renghadi. This sparked the Renghadi to enter the war, alongside the rest of the Velarian Confederation (that being the Catavalans, Donburil, Fassai, Quagi, and Velarians).
This helped turn the tide of the war, but it wasn't until 2008 that the Jhinu's coffin got its final nail. An exploration vessel full of Sholarron saw the carnage of the war and appealed to the rest of the Se'ecra Combine (that being the Dorvalans, Ixendar, Jaruma, R'kaili, Se-lag, Se'ecra, and Susethrin) to join in. The Combine agreed and the Jhinu were forced to surrender in 2009 after they lost the Battle of Gary on Terra.
Over two billion sophonts were killed across 31 species during the war. But after the war, the Jhinu begrudgingly agreed to sulk on their homeworld, and as of today, many government officials have turned to piracy as the resistance makes great strides.
As for the 30 victorious species, they allied together into the Orion Alliance. The formation of the Orion Alliance sparked intrigue from a power who had been oblivious to all this fighting, the Ackálian Empire. Being impressed by the war stories, the Ackálian Empress decided to let the species of the Empire hold referenda on whether they wanted to leave the Empire and join the Alliance. In the end, 15 of the Empire's 18 subject races left, and the Orion Alliance welcomed the Belaxians, Dendrians, Dorugandans, Ereni, Esagites, Gadroon, Hrac'darese, Kadilians, Kolajik, Mostreen, Nan, Pograckians, Salgandans, Shar'een, and Vayathurans.
Since the Ackálian referenda, the Orion Alliance has only welcomed five more races, those being the Krsst, Malvans, Prylenish, Qedustiers, and Zmm.
So far, no other aliens have shown interest in joining, but one could always be in the next solar system over.