Sloth
Sloths have existed in various forms for approximately sixty million years. The modern two-toed and three-toed varieties have occupied their ecological niche since long before humans developed the cognitive capacity to find them endearing. Their survival strategy of moving so slowly that predators lose interest has proven remarkably durable.
Mickey Mouse
Mickey Mouse first appeared in Steamboat Willie in 1928, making him ninety-six years old in biological terms. In brand years, however, Mickey has achieved a form of corporate immortality through aggressive copyright extension. Disney's legal team has ensured Mickey will likely outlive most current nation-states.
VERDICT
The sloth wins decisively with a sixty-million-year head start. Whilst Mickey's corporate immortality project shows promise, he has not yet demonstrated the ability to survive an asteroid impact, an ice age, or the rise and fall of countless apex predators. The sloth has survived them all, primarily by hanging motionless and waiting.