The Siamese cats are the antagonists in "Growltiger's Last Stand", in which Gus reminisces about a performance in which he played Growltiger, a ferocious pirate who was taken down by the Siamese crew, led by Gilbert / Genghis.
The Siamese cats are portrayed as ruthless, efficient, yet possibly merciful towards Griddlebone. It is sometimes implied that Griddlebone may have been in cahoots with the Siamese all along, intentionally distracting Growltiger so that the Siamese can take him down.
As the Siamese are performed by most of the cast, one of the male cast members will double as Gilbert / Genghis.
In the original Broadway Production, the role was renamed "Genghis", and this was subsequently adopted by most productions, with alternate spellings including "Ghengis" and "Gengis". Carbucketty initially doubled the role of lead Siamese on Broadway, but after the role of Carbucketty was cut in 1987, Genghis went to the actor who played Mungojerrie. Mungojerrie would double the part again in the 1st US tour, 5th US tour and the 1991 Zurich production.
But most to cats of foreign race his hatred had been vowed
To cats of foreign name and race, no quarter was allowed
The Persian and the Siamese regarded him with fear
Because it was a Siamese had mauled his missing ear
And his raffish crew were sleeping in their barrels and their bunks
As the Siamese came creeping in their sampans and their junks
Growltiger had no eye or ear for aught but Griddlebone
And the lady seemed enraptured by my manly baritone
Disposed to relaxation and awaiting no surprise
But the moonlight shone reflected from a thousand bright blue eyes
And closer still and closer the sampans circled 'round
And yet from all the enemy there was not heard a sound
The foe was armed with toasting forks and cruel carving knives
And the lovers sang their last duet in danger of their lives
Then Genghis gave the signal to his fierce Mongolian horde
With a frightful burst of fireworks, the siamese swarmed aboard
Abandoning their sampans, their pullaways, and junks
They battened down the hatches on the crew within their bunks
Then Griddlebone she gave a screech for she was badly skeered
I am sorry to admit it, but she quickly disappeared
She probably escaped with ease I'm sure she was not drowned
But a serried ring of flashing steel Growltiger did surround
The ruthless foe pressed forward in stubborn rank on rank
Growltiger to his vast surprise was forced to walk the plank
He who a hundred victims had driven to that drop
At the end of all his crimes was forced to go kerflip, kerflop
Oh there was joy in Wapping when the news flew through the land
At Maidenhead and Henley there was dancing on the Strand
Rats were roasted whole in Brentford and Victoria Dock
And a day of celebration was commanded in Bangkok!
The original London production dressed the Siamese characters in simple, generic "Asian" style robes patterned with triangular blue-eyed Siamese cat faces. The choreography included large fans.
The Broadway production, the following year, had a far larger budget for costumes and the Siamese upgraded to some of the most intricate and complex costumes in the show. Patterned after historic Thai Armour, they included complex headdress, a broad collar with pointed shoulders, and a tabard, worn over fawn to brown ombre satin. The collar and tabard included electrified light-up blue eyes that glowed. They also gained the prop carving knives and toasting forks as mentioned in the lyrics. These more elaborate designs became the standard world-wide and replaced the simple fan costumes in the UK by the mid-1990s.
The portrayal of the Siamese has been condemned by both critics and fans for its dated and offensive racial stereotypes. However "Growltiger's Last Stand" has been gradually phased out in UK and US productions from 2016 onwards.