The Komodo dragon is more likely to win a fight against a tiger. Komodo dragons have a combination of armor, agility and venom that protects them and would aid them in killing the tiger.
In May 2009, venom was discovered to be the primary way in which Komodos bring down prey. Komodo dragons grow to nearly 10 feet, weigh approximately 150 pounds and have an armor plating. A tiger is an aggressive fighter, but its larger size brings agility and speed into consideration, while the Komodo dragon needs one bite of venom to kill the tiger.
Komodo dragons are the largest known lizards in existence, and they are descendants of the Megalania, which populated the Australian continent 40,000 years ago.