Migraine
The name is Roach. Cock Roach.
Timex?
Kaiser Soze, he showed men of will what will really was. Really, there are some great lines describing him and his inability to die.
That’s one of the reasons we’re planning to name our next cat The Magnificent Fangmeyer. 
Instead of Terminator, how about T100? Arnold?
Jack Sparrow?
Tom Tresser? (The comic books’ “Nemesis,” he’s been killed off at least twice, in addition to a stint in a Russian prison. He’s currently dating Wonder Woman. But then that sort of career is normal for his genre–except for dating Wonder Woman.)
Samsonite?
But Michael Malloy is cool.
not pooty poot?
“The Stupidity of The Masses” would be a bad name for a cat, but it does live up to surviving-well-beyond-the-expected-threshold.
Maybe “Stain” or “Rich Uncle.”
I came in here to suggest T-1000. Arnold’s character’s model number was T-800, which would work too.
Aha! I have it.
Named the little guy after kudzu, the unkillable weed that gets into everything.
Or call him Catzu.
Catzu. Gesundheit!
Since he survived a harrowing frozen adventure, what about Shackleton?
Wile E. [Coyote]?
Adolphe Sax, musical instrument maker (saxophones and saxhorns are just two of his brainchildren).
Known as Le Revenant (The Ghost Child) for several close calls during his youth, including falling out of a second-story window and setting himself on fire, Sax later survived two assassination attempts by rival manufacturers and a rather gross case of lip cancer probably caused by exposure to brass filings.
Dangit, I was going to mention Shadrach, Meshach, and Abednego.
Gloria Gaynor! He could have his own theme song.
I love the name Malloy for a cat.
I was thinking highlander, you basically have to cut its head off to kill one.
Yuschenko? Viktor Yushchenko - Wikipedia
:eek: I had no idea the musical instrument business was so competitive!
Frunobulax
My first thought was Shackleton, but Durer beat me to it. Maybe Ernie?
For indestructibility, there’s always Rocky.
May I suggest Mrs Whatsit
Oooooooh, a good call. If the cat was a she, you could go for the next generation of unkillable and name her Amy Winehouse
Although, Shackleton is full of awesome.