Trophies - Successfully complete one of the following tasks to get a trophy:

Corinth Ribbon (Bronze): Complete Corinth River on any difficulty level.
Blood Ribbon (Bronze): Complete Blood Meridian on any difficulty level.
Visari Ribbon (Bronze): Complete Visari Square on any difficulty level.
Salamun Ribbon (Bronze): Complete Salamun District on any difficulty level.
Bridge Ribbon (Bronze): Complete Salamun Bridge on any difficulty level.
Suljeva Ribbon (Bronze): Complete Suljeva Village on any difficulty level.
Tharsis Ribbon (Bronze): Complete Tharsis Refinery on any difficulty level.
Cruiser Ribbon (Bronze): Complete The Cruiser on any difficulty level.
Popcorn Ribbon (Bronze): Watch all Killzone 2 cut scenes.
Pallbearer (Bronze): Kill 20 Helghast soldiers.
Undertaker (Bronze): Kill 200 Helghast soldiers.
Reaper (Bronze): Kill 1000 Helghast soldiers.
Field Agent (Bronze): Collect all intel within the game.
Iconoclast (Bronze): Destroy all Helghast symbols within the game.
Untouchable (Bronze): Complete all missions on any difficulty level without dying.
Babysitter (Bronze): Revive your buddies a total of 25 times.
Safari Hunter (Bronze): Kill one of each enemy type with a melee attack.
Killing Spree (Bronze): Kill 5 Helghast in 15 seconds whilst on foot and maintaining at least 85 % health.
Bullet Counter (Bronze): Manually reloaded your weapon 150 times..
Safety first (Bronze): Shoot off 100 Helghast helmets during battle.
Berserker (Bronze): Kill 25 Helghast using melee attacks.
Barrel of Death (Bronze): Kill 2 Helghast at once using the surrounding environment.
Professional (Bronze): Get 3 headshots in a row using the M4 Revolver.
Fragmerchant (Bronze): Kill 3 Helghast at once using a single frag grenade.
Fragmartyr (Bronze): Kill 2 Helghast at once and take your own life using a single frag grenade.
Melonpopper (Bronze): Get 15 headshots using the PR-6 sniper rifle.
Blade Runner (Bronze): Kill 10 Helghast using the knife.
Run and Gunner (Bronze): Kill 3 Helghast with one burst of an M82 or StA52 assault rifle.
Defensive Fighter (Bronze): Killed 30 Helghast with an emplaced weapon.
Valor Medal (Bronze): Achieve weekly online honor rank #2.
Valor Citation (Bronze): Achieve weekly online honor rank #1.
Cross-Training Ribbon (Bronze): Acquire all badge specific medals.
Veteran Ribbon (Bronze): Acquire all mission specific medals.
Expert Ribbon (Bronze): Acquire all combat specific medals.
Wargod Ribbon (Bronze): Acquire the Wargod Ribbon.
Blitzkrieg Ribbon (Bronze): Win 50 online matches.
Maelstra Ribbon (Silver): Complete Maelstra Barrens on any difficulty level.
Survivor (Silver): Complete all missons on any difficulty level.
Valor Cross (Silver): Achieve weekly online honor rank #3.
Complete all missions (Gold): Complete all missions on Elite difficulty level.
Career Ribbon (Gold): Achieve an online rank of General.
Valor Grand Cross (Gold): Achieve weekly online honor rank #4.
Platinum (Platinum): Collect all Killzone 2 Trophies.

Additionally, there are ten secret trophies:

Elementalslayer (Bronze): Kill the Tharsis Refinery ArcTrooper in under 1 minute 30 seconds.
Giantslayer (Bronze): Kill the Blood Meridian Heavy in unter 1 minute.
Dragonslayer (Bronze): Kill the Salamun Bridge ATAC in under 1 minute 30 seconds.
Demonslayer (Bronze): Kill Radec at Visari Palace within 20 minutes.
Stick Around (Bronze): Nail 20 Helghast to a wall using the Boltgun VC-21.
Master Conductor (Bronze): Electrocute 3 Helghast with a single burst from the AR-X.
Can Opener (Bronze): Destroy a Helghast APC during battle.
Spare Parts (Bronze): Destroy all Leech Pods in The Cruiser.
Treadhead (Bronze): Kill 30 Helghast whilst using the ISA tank.
Mechspert (Bronze): Stomp 10 Helghast with your Exoskeleton in Maelstra Barrens.