Here is the full list of all 38 Thief trophies - there are 24 bronze, 8 silver, 5 gold and 1 platinum.
The True Master Thief
Score an epic 5,000,000 or more in a Challenge Map
Discover all secret areas
Use 40,000 gold
Complete all collectible sets
Shoot a bottle in mid-air with an arrow
Find all the secret stashes in Moira
Complete 25 optional Thieving Challenges
Finish the game on Master difficulty
Finish the game with a custom difficulty of 700 points or more
Finish the game without a single kill or knockout
Reach the final chapter without using the focus ability
Finish Chapter Eight
Finish the game in 15 hours or more
Finish Chapter Seven
Pick 100 pockets in a single playthrough
Complete all Client Jobs in The City
Complete a collectible set
Complete all Basso Jobs in The City
Complete 10 optional Thieving Challenges
Kill or knockout 10 people using the environment
Finish Chapter Six
Discover 15 secret areas
Disarm ten trap mechanisms
Finish Chapter Five
Pick a pocket and a lock using the focus ability
Finish Chapter Four
Finish Chapter Three
Steal all loot and collectibles in a single chapter
Uncover Lyegrove's secret
Finish Chapter Two
Finish 3 consecutive missions without taking damage
Steal 5 collectibles
Sweet sixteen. Snuff said.
Pick a lock with masterful speed
Finish a single chapter without alerting anyone
Finish Chapter One
Finish the Prologue