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The scientists in their original (top) and HD pack (bottom) forms.
From left to right: Glasses, Einstein, Luther, Slick

monster_scientist is a point entity available in Half-Life Half-Life, Half-Life: Opposing Force Half-Life: Opposing Force, and Half-Life: Blue Shift Half-Life: Blue Shift.

The Black Mesa science personnel. They can follow the player and administer weak antidote for wounds. They're sometimes required in gameplay for access to otherwise restricted areas through retinal scanners.

Note.pngNote:Using the "Pre-Disaster" spawnflag will make this entity refuse to follow the player.


Note.pngNote:Some keyvalues, flags, inputs, or outputs might not affect an NPC, based on the functionality and coding of the NPC.

Body (???) <choices>
Only difference is appearance. Some alter the pitch of the sentences they speak.
Value Description
-1 Random
0 Glasses (aka "Walter" or "Kleiner")
1 Einstein (aka "Coomer")
2 Luther (aka "Eli")
3 Slick

Use Sentence <string>
The name of a sentence that plays when the player brings the NPC into their group. Example: "All right let's go, I didn't wanna die alone anyway."
Un-Use Sentence <string>
The name of a sentence that plays when the player removes the NPC from their group. Example: "All right, I'll stay right here."


TriggerTarget (???) <string>
Name of entity to target when the trigger conditions are met.
Trigger Condition (???) <choices>
Condition to use for TriggerTarget
  • 0 : "No Trigger"
  • 1 : "See Player, Mad at Player"
  • 2 : "Take Damage"
  • 3 : "50% Health Remaining"
  • 4 : "Death"
  • 7 : "Hear World"
  • 8 : "Hear Player"
  • 9 : "Hear Combat"
  • 10: "See Player Unconditional"
  • 11: "See Player, Not In Combat"


Target (???) <targetname>
The targetname of the first path_corner in a path this monster will move to when spawned.

Name (targetname) <targetname>
The targetname that other entities refer to this entity by.
Render FX (renderfx) <choices>
Render FX mode to use, for special effects.
Value Description
0 Normal
1 Slow Pulse
2 Fast Pulse
3 Slow Wide Pulse
4 Fast Wide Pulse
5 Slow Fade Away
6 Fast Fade Away
7 Slow Become Solid
8 Fast Become Solid
9 Slow Strobe
10 Fast Strobe
11 Faster Strobe
12 Slow Flicker
13 Fast Flicker
14 Constant Glow
15 Distort
16 Hologram (Distort + fade)
Render Mode (rendermode) <choices>
Render Mode to use.
Value Description
0 Normal
1 Color
2 Texture
3 Glow
4 Solid
5 Additive
FX Amount (1-255) (renderamt) <integer>
Controls transparency when using another render mode then normal. 0 is completely invisible, and 255 is opaque.
FX Color (R G B) (rendercolor) <color255>
Color to use by the specified render mode.
Also used to control the speed of scrolling textures; see func_conveyor for more information.


Pitch Yaw Roll (Y Z X) (angles) <angle>
This entity's orientation in the world. Pitch is rotation around the Y axis, yaw is the rotation around the Z axis, roll is the rotation around the X axis.

GoldSrc flags

  •  [1] : Wait Till Seen
  •  [2] : Gag (No IDLE sounds until angry)
  •  [4] : MonsterClip
  •  [8] : No wreckage
  •  [16] : Prisoner
  •  [64] : Start inactive
  •  [128] : Wait for script
  •  [512] : Fade corpse
  •  [2048] : Not in Deathmatch
       !FGD for some entities.