Here is the full list of all 37 Snipers - Invisible, Silent, Deadly trophies - there are 22 bronze, 9 silver, 5 gold and 1 platinum.
Gain all the trophies.
Finish the tutorial.
Succeed at all the challenges from level 3.
Succeed all Level I challenges.
Reach the highest rank (Commander)
Win a match on each map for each game mode.
Win a Contract match.
Win a game in each game mode.
Kill multiple enemies with an explosive.
Purchase all Abilities equipment.
Purchase all equipment.
Be promoted to Lieutenant I.
Win a Last Team Standing game.
Kill an enemy caught up in his grappling gear.
Purchase all Scope equipment.
Finish off an enemy who has been stunned by a stun grenade.
Win a Team Deathmatch.
Destroy an enemy explosive.
Purchase all Booby traps equipment.
Kill an enemy with a silencer.
Win a Capture the Flag game.
Purchase all Projectiles equipment.
Purchase all weapons.
First weapons purchase.
First equipment purchase.
Kill an enemy through a wall.
Win a game on each map.
Be promoted to Sergeant.
Succeed a Level III challenge
Kill an enemy and yourself with a grenade.
Kill an enemy by sending his own grenade back to him.
Kill an enemy with an explosive.
Win a Free For All game.
Stab an enemy to death.
Stab an enemy in the back.
First use of a Drone.
Kill an enemy with a headshot.