Left 4 Dead

1. 
   DEAD STOP

   Punch a Hunter as he is pouncing.
   32%
2. 
   DRAG AND DROP

   Rescue a Survivor from a Smoker's tongue before he takes damage.
   62%
3. 
   CR0WND

   Kill a Witch with a single headshot.
   11%
4. 
   UNTOUCHABLES

   No Survivors take damage after contacting the rescue vehicle.
   8.2%
5. 
   BLIND LUCK

   You or another Survivor take no damage after being vomited on by a Boomer.
   51%
6. 
   MY BODYGUARD

   Protect any Survivor from an attacking Infected 50 times.
   40%
7. 
   AKIMBO ASSASSIN

   Survive an entire campaign using only pistols.
   7.5%
8. 
   FIELD MEDIC

   Heal 25 Survivors with a first aid kit.
   11%
9. 
   PHARM-ASSIST

   Give pain pills to 10 Survivors.
   14%
10. 
    HELPING HAND

    Revive 50 incapacitated Survivors.
    14%
11. 
    HERO CLOSET

    Rescue a Survivor trapped in a closet.
    42%
12. 
    HUNTER PUNTER

    Shove a Hunter off of a pinned and helpless Survivor.
    38%
13. 
    TONGUE TWISTER

    Kill a Smoker who has grabbed you with his tongue.
    57%
14. 
    NO SMOKING SECTION

    Kill 10 Smokers as they are pulling helpless Survivors.
    34%
15. 
    101 CREMATIONS

    Set 101 Infected on fire.
    38%
16. 
    DO NOT DISTURB

    Sneak past all Witches in a campaign without disturbing one.
    13%
17. 
    MAN VS TANK

    Single-handedly kill a Tank.
    7.8%
18. 
    TANKBUSTERS

    Kill a Tank without it dealing any damage to a Survivor.
    55%
19. 
    SAFETY FIRST

    Play an entire campaign with no Survivors taking friendly fire damage.
    4.0%
20. 
    NO-ONE LEFT BEHIND

    Beat a campaign with all 4 Survivors.
    40%
21. 
    UNBREAKABLE

    Finish a campaign without ever using a first aid kit on yourself.
    6.3%
22. 
    WITCH HUNTER

    Kill a Witch without any Survivor taking damage from her.
    38%
23. 
    RED MIST

    Kill 1000 Infected with a mounted machine gun.
    5.0%
24. 
    PYROTECHNICIAN

    Blow up 20 Infected in a single explosion.
    49%
25. 
    ZOMBIE GENOCIDEST

    Kill 53,595 Infected.
    4.5%
26. 
    DEAD GIVEAWAY

    Heal a fellow Survivor when your own health is below 10.
    16%
27. 
    GROUND COVER

    Save another Survivor from a Special Infected while on the ground.
    24%
28. 
    CLEAN KILL

    Shove a Boomer and then kill him without him splashing on anyone.
    22%
29. 
    STAND TALL

    Survive a campaign without being incapacitated.
    20%
30. 
    BACK 2 HELP

    Leave a safe room to save an incapped teammate and bring them back safely.
    13%
31. 
    ZOMBICIDAL MANIAC

    Survive any campaign on Expert.
    6.5%
32. 
    WHAT ARE YOU TRYING TO PROVE?

    Survive all campaigns on Expert.
    3.6%
33. 
    NOTHING SPECIAL

    Survive a campaign with no Survivors taking damage from Special Infected.
    2.9%
34. 
    BURN THE WITCH

    Light a Witch with a Molotov.
    32%
35. 
    TOWERING INFERNO

    Light a Tank with a Molotov.
    46%
36. 
    SPINAL TAP

    Kill an Infected with a single blow from behind.
    33%
37. 
    STOMACH UPSET

    All Survivors complete a campaign without being vomited on.
    7.2%
38. 
    BRAIN SALAD

    Make 100 headshot kills.
    53%
39. 
    JUMP SHOT

    Headshot a Hunter while he's leaping.
    27%
40. 
    MERCY KILLER

    Survive the No Mercy campaign.
    34%
41. 
    TOLL COLLECTOR

    Survive the Death Toll campaign.
    24%
42. 
    DEAD BARON

    Survive the Dead Air campaign.
    24%
43. 
    GRIM REAPER

    Survive the Blood Harvest campaign.
    21%
44. 
    BARF BAGGED

    Cover four Survivors with Boomer bile at once.
    8.8%
45. 
    BIG DRAG

    Drag a Survivor 100 feet with your tongue as a Smoker.
    10%
46. 
    CHAIN SMOKER

    Constrict two Survivors on one life as a Smoker.
    14%
47. 
    DOUBLE JUMP

    Pounce two different Survivors on one life as a Hunter.
    15%
48. 
    All 4 Dead

    Kill all four Survivors on one life as a Tank.
    7.6%
49. 
    DEAD WRECKENING

    Dole out 5000 total Survivor damage as a Special Infected.
    9.3%
50. 
    LAMB 2 SLAUGHTER

    As an Infected, incap a Survivor who has entered and left a safe room.
    10%
51. 
    OUTBREAK

    Catch a rare strain of infection, then pass it on to someone else.
    22%
52. 
    LAST STAND

    Complete one round of Survival on The Last Stand.
    13%
53. 
    BRONZE METTLE

    Earn a Bronze medal in Survival mode on any official level.
    16%
54. 
    SILVER BULLETS

    Earn a Silver medal in Survival mode on any official level.
    11%
55. 
    VIOLENCE IS GOLDEN

    Earn a Gold medal in Survival mode on any official level.
    9.4%
56. 
    DISTINGUISHED SURVIVOR

    Earn at least a Bronze medal on every official Survival level.
    3.3%
57. 
    HEROIC SURVIVOR

    Earn at least a Silver medal on every official Survival level.
    2.8%
58. 
    LEGENDARY SURVIVOR

    Earn a Gold medal on every official Survival level.
    2.7%
59. 
    CRASH-PROOF

    Survive the Crash Course Campaign.
    25%
60. 
    QUICK POWER

    Restart the generator within 30 seconds of it shutting off.
    14%
61. 
    THE LITTLEST GENOCIDE

    Kill 5,359 Infected in the Crash Course campaign.
    3.4%
62. 
    SMASH HIT

    Win a Versus campaign of Crash Course.
    5.6%
63. 
    TRUCK STOP

    Your team wipes all Survivors after the escape vehicle has opened in Crash Course.
    2.7%
64. 
    20 CAR PILE-UP

    As A Tank hit 20 Survivors with a car in the Crash Course campaign.
    2.4%
65. 
    JUMPIN' JACK SMASH

    Pounce a Survivor for 25 points of damage in the Crash Course campaign.
    3.0%
66. 
    SLIPPERY PULL

    Smoker pull a bile-covered Survivor until you hold him during Crash Course.
    3.9%
67. 
    TANK STUMBLE

    Stun a Tank with an explosion in the Crash Course campaign.
    8.7%
68. 
    WIPEFEST

    Your team incapacitates three Survivors within five seconds.
    3.7%
69. 
    Supreme Sacrifice

    Complete "The Sacrifice".
    9.0%
70. 
    Kill Bill

    Have Bill sacrifice himself for the team.
    6.2%
71. 
    Barrel Rolled

    Kill a Special Infected with an exploding barrel.
    3.4%
72. 
    Chaos Generator

    Have all 3 generators running at once in "The Sacrifice" finale.
    4.1%
73. 
    Sacrifizzle

    As a Special Infected, incap someone who is trying to sacrifice themselves.
    2.5%

Names, descriptions and icons are the game’s own, as Steam publishes them; the share is how many owners have unlocked each, from Steam's global figures for 73 of them.