Actor

AActor — the base class for everything placeable in a level.

Lifecycle

Spawn / Load
  ↓ PostInitializeComponents()
  ↓ BeginPlay()
  ↓ Tick() repeatedly
  ↓ EndPlay()
  ↓ Destroy()

Equivalent BP events:

Event	When
Construction Script	At spawn / editor change
Begin Play	Game starts or actor spawns at runtime
End Play	Destroyed, level transition, game over
Tick	Every frame (if Actor Tick Enabled)
Actor Begin Overlap / Actor End Overlap	Collision events

Required components on a spawnable actor

• A RootComponent (any USceneComponent). Without one, the actor has no transform.
• Optional: UStaticMeshComponent, UBoxComponent (collision), UAudioComponent, etc.

Replication

Set Replicates = true in the Class Defaults. Then per-property: mark with Replicated (BP) or UPROPERTY(Replicated) (C++) and override GetLifetimeReplicatedProps.

void AMyActor::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& Out) const
{
    Super::GetLifetimeReplicatedProps(Out);
    DOREPLIFETIME(AMyActor, Health);
}

Levels

Every actor belongs to a level. The level's Level Blueprint (ALevelScriptActor) has access to all actors in that level.

In World Partition maps, actors are stored as One File Per Actor (OFPA) — each actor is a separate .uasset file. See Tools → One File Per Actor.

Common derived classes

Class	Use
APawn	Possess-able by a Controller
ACharacter	Pawn + CharacterMovementComponent + Capsule + SkeletalMesh
AVolume	Bounded region — see Volumes
APlayerCameraManager	Owns the camera POV for a player
AGameModeBase	Server-side game rules; not replicated
AGameStateBase	Replicated server state

See also

• Components
• Volumes
• Networking → Replication