|Time period:||2807 – 2868|
|Capital world:||was Shadow??|
|Military:||Clan Mongoose Touman|
|Secret Service:||Clan Mongoose Watch|
The Clan Mongoose home planet of Shadow was also where the clan's totem-animal originated. Adopted from the animal that killed the dangerous Venom Worms, which were a great threat to humans, and as such endeared the mongoose to the Clan. The Clan is no longer in existence.
 Operation Klondike
 InterClan Conflicts
After the annihilation of Clan Wolverine, Khan Loris of Clan Mongoose attempted to exert control over Clan Snow Raven, which had been badly wounded by the Wolverines. Loris withdrew his attempts at Absorption when the Snow Raven Khan Stephen McKenna threatened to give the Grand Council tapes proving a personal connection between Khan Loris and Khan Sarah McEvedy of the Wolverines. Clan Mongoose also struck ruthlessly at Clan Blood Spirit, often disregarding Clan rules of engagement.
In 2844, motivated by jealousy, the Mongoose warriors struck at Clan Star Adder and ruthlessly massacred the Adder colonists on Marshall. The outraged Star Adders took their revenge by wiping out the entire Mongoose attack force. In retaliation, the same Star Adder commander moved and conquered the Mongoose colony on Tokasha. They, then had entire former Mongoose population of the enclave transported to Marshall where they were used to repopulate Star Adder's enclave. The Mongoose Clan was no match for the Star Adders but once they obtained the OmniMech technology, they hit the Star Adders in force. However, they overextended themselves and the Adders managed to obtain the new technology and struck back. Just as the Star Adder assaults were winding down, Clan Mongoose attacked Clan Smoke Jaguar, but was soundly beaten.
 Absorption and Legacy
During the early years of the Golden Century, many conflicts would arise as the Clans expanded to fill up the volume of the Kerensky Cluster. Clans that used their resources for exploration and colonizing often had to defend their investments from another Clan that was waiting to poach the fruits of their labor with military strength. Surprisingly, the most aggressive Clan of this era was not the Smoke Jaguars, despite being well-known for their casual brutality. That distinction belonged to Clan Mongoose. Driven by Khans who mortally feared showing any martial weakness to their competitors, they were almost as infamous for their incessant attacks on many of their neighbors as they were for their constant political maneuvering, which had over the years earned for their Clan the nickname "the Weasels". The Clans targeted for their predations included, but certainly were not limited to, Clan Blood Spirit during the years after the Annihilation of the Not-Named Clan, and later, Clan Star Adder.
In 2868, the Mongooses geared up for a strike against the Smoke Jaguars on the colony world of Atreus as part of an ongoing feud with that Clan. Just as they launched this attack, the Star Adders launched their own multi-world assault on Clan Mongoose in revenge for the loss of nearly half their colony worlds five years earlier. Colony after colony fell to the well-executed plans of the Star Adders and their Khan. The disrupted Mongoose attack against the Smoke Jaguars on Atreus was soundly defeated. This turn of events would lead Khan Walter Martindale of Clan Mongoose to hastily bring charges against Clan Smoke Jaguar in the Grand Council, accusing them of starting a wasteful conflict. While this was a blatantly obvious ploy to stall for time in which to get his Clan out of the pit it had dug for itself, what decided his fate - as well as the fate of every other Mongoose citizen - was his shameless use of the Great Kerensky's words in an attempt to bolster his position. Infuriated by this sickening display of political maneuver, Smoke Jaguar Khan Theodore Osis would declare the Mongoose leaders incapable of ruling their citizens. Calling Khan Martindale's citation of the Great Kerensky's words in a ploy to cover his Clan's weakness an act of Treason against the Grand Council, Khan Osis would immediately demand a Trial of Absorption against their Clan. The Grand Council had seen far too many political stunts by the Mongoose Khans during the past few decades, and voted in favor of the Smoke Jaguar Khan's motion. Clan Mongoose would have little time to prepare their already damaged Touman for the onslaught ahead.
Wasting no time, the Smoke Jaguar WarShip fleet attacked the Mongoose fleet above Circe. After the appearance of the Quicksilver Mongoose, the Mongoose's flagship, the battle nearly tipped in their favor, as it destroyed its Clan Smoke Jaguar counterpart, the McKenna-class Obsidian. But after engagement by the Lola III-class Storm Cat, it was crippled and allowed to drift into space, leaking atmosphere from its shattered frame. A large part of the Mongoose's Aerospace Fighters made their appearance above Circe, inflicting heavy loses on the Jaguars. By the end of the engagement, the bulk of the Mongoose fleet had been destroyed, but only at a high price paid by the Jaguar's space forces.
Next, the Smoke Jaguars would hit the now isolated Mongoose colonies remaining in the Kerensky Cluster. At the Mongoose colony on Atreus, the Smoke Jaguars would win after a conflict that ground both sides down to dust. After the initial pitched battle, remnants of the Mongoose naval and aerospace forces rallied to nearly retake the spaceport, but ultimately failed to do so. On Kirin, the battle would be even more protracted. The Mongoose defenders brought in most of their remaining Aerospace forces, which were still considerable. In spite of a few flashes of hope in these battles, as well as the inflicting of heavy casualties on the Jaguar attackers, the Mongoose defenders were inevitably destroyed, or surrendered.
Finally, Circe was the only Mongoose enclave left. After taking the Mongoose territory on the main continent, defended by the Mongoose solahma, the Smoke Jaguars would run up against the island fortress of Fianna. With heavy defenses and even a blue navy to patrol the surrounding waters, the Mongooose warriors were optimistic about being able to hold out for years against their slowly-weakening attackers. The problem was solved when Khan Osis asked ilKhan Zenos Danforth and the Grand Council for the right to use Orbital Bombardment against the Mongoose stronghold. His request would be granted. Unknown to all, Clan Mongoose Khan Walter Martindale perished during the bombardment, a fact that if known could have ended the Trial then and there. After raining destruction down on the western shores of Fianna, the Jaguar forces poured onto the island to finish off their enemy. With Khan Osis personally leading his forces against the final defenses arrayed against them in the city of Tara, Mongoose saKhan Alanah Knox led her Keshik against the Jaguar Khan's flanks, inflicting more casualties than they took, while the last few Aerospace Fighters covered their maneuvers. But it was simply too late. This last, desperate attack would be the final act of a doomed Clan.
All Mongoose assets became the property of the Smoke Jaguars, greatly enriching them. The Grand Council would even allow them to trade land to certain Clans for the right to take an unspecified amount of WarShips (but not many) from naval caches in order to recoup losses to their shattered fleet. But Khan Osis would cast aside the genetic legacies of all Mongoose warriors, boasting that his Clan "will never use the tainted genes of these schemers", desiring that the vanquished Clan fade away. Later, the Cloud Cobras led by a bold Khan Josef Mannix would bid for and win the rights to over 70 legacies from 11 different Bloodnames, mostly aerospace pilot legacies. The Smoke Jaguars would be angry over the Cloud Cobra's decision to activate these lines, but there was little they could do to defend legacies that they had scorned.
By 3067, a single WarShip of the Clan remained in mothballs in the Clan Capital system of Strana Mechty. The ancient Du Shi Wang-class Battleship, the Quicksilver Mongoose, had faithfully served the Clan until the Clan's ultimate demise. 
- Mitchell Loris, 2807 - ????
- Davis Riley (Khan in 2844)
- Jes Greenhalgh (Khan in 2845)
- Walter Martindale, ???? - 2868
- ↑ The Clans: Warriors of Kerensky, p. 108, "Marshall" - Star Adders strike Tokasha's Mongoose populations and removes from the planet.
- ↑ Historical: Operation Klondike, p. 92, 93 - "A Legacy of Violence: The Jaguar pounces"
- ↑ Era Digest: Golden Century, p. 11, 12 - "Life as a Mongoose"
- ↑ 4.0 4.1 Invading Clans, p. 49, 50 - "The Golden Century"
- ↑ 5.0 5.1 5.2 5.3 Era Digest: Golden Century, p. 7, 8 - "Warriors above Politicians"
- ↑ 6.0 6.1 Field Manual: Crusader Clans p. 112, 113 - "Into the Golden Century"
- ↑ Era Digest: Golden Century, p. 11, 12 - "Warriors Above politicians"
- ↑ 8.0 8.1 8.2 Era Digest: Golden Century, p. 12 - "Beginning of the End"
- ↑ 9.0 9.1 Era Digest: Golden Century, p. 9 - "Warriors Above Politicians"
- ↑ Field Manual: Warden Clans, p. 21, 22 - "Maturation Amid the Renaissance"
- ↑ Technical Readout: 3075, p. 252, "Du Shi Wang" - former Capellan Battleship served Mongooses until their demise.
- ↑ Historical: Operation Klondike, p. 71
- ↑ Technical Readout: 3067, p. 160
- ↑ Master Unit List, Chaeronea
- ↑ Era Digest: Golden Century, p. 8, 10
- ↑ Historical: Operation Klondike, p. 71
- ↑ Era Digest: Golden Century, p. 9, 10
- ↑ Era Digest: Golden Century, p. 10, 11