From Quake Wiki
Knights have a sharp sword and strong arms, but their drawback is their lack of a ranged attack. Two good spanks from the Double-Barrelled Shotgun will work (or, more efficiently, a Shotgun blast immediately followed by a double-barrelled shot).
monster_knight is the entity for placing Knights in a level.
|targetname||The targetname of the Knight. When triggered, the Knight will wake up if inactive.|
|target||The targetname of the entity to be triggered when the Knight dies.|
|killtarget||The targetname of the entity to be removed when the Knight dies.|
The monster_knight entity supports the following spawnflags:
|1||Ambush||The Knight will not wake up from seeing other monsters wake up or hearing sounds.|
It also supports the standard spawnflags for difficulty and deathmatch presence.
|256||Not on Easy||The Knight will not spawn on Easy difficulty.|
|512||Not on Normal||The Knight will not spawn on Normal difficulty.|
|1024||Not on Hard||The Knight will not spawn on Hard difficulty.|
|2048||Not in Deathmatch||The Knight will not spawn in Deathmatch mode.|
This is the format used by TrenchBroom and Worldcraft. Note that the model(...) parameter is not supported by Worldcraft. This does not include the Monster base class definition, which is also required.
@PointClass base(Monster) size(-16 -16 -24, 16 16 40) model(":progs/knight.mdl") = monster_knight: "Knight" 
This is the definition format used for most old Quake editors, including the original QuakeEd.
/*QUAKED monster_knight (1 0 0) (-16 -16 -24) (16 16 40) Ambush */