Standard Assets (for Unity 2018.4)
Unity Technologies
★★★★
Free Download

Free Platform Game Assets
Bayat Games
★★★★★
Free Download

Sunny Land
Ansimuz
★★★★★
Free Download

Terrain Tools Sample Asset Pack
Unity Technologies
★★★★★
Free Download

3D Game Kit
Unity Technologies
★★★★
Free Download

AllSky Free - 10 Sky / Skybox Set
rpgwhitelock
★★★★★
Free Download

Dream Forest Tree
IL.ranch
★★★★
Free Download

Oculus Integration
Oculus
★★★
Free Download

Unity-Chan! Model
unity-chan!
★★★★★
Free Download

Unity Particle Pack
Unity Technologies
★★★★
Free Download

Nature Starter Kit 2
Shapes
★★★★★
Free Download

Joystick Pack
Fenerax Studios
★★★★★
Free Download

Basic Motions FREE Pack
Kevin Iglesias
★★★★★
Free Download

PUN 2 - FREE
Exit Games
★★★★
Free Download

DOTween (HOTween v2)
Demigiant
★★★★★
Free Download

Unity Particle Pack 5.x
Unity Technologies
★★★★★
Free Download

Low-Poly Simple Nature Pack
JustCreate
★★★★★
Free Download

First Person All-in-One
Aedan Graves
★★★★★
Free Download

Space Robot Kyle
Unity Technologies
★★★★
Free Download

2D Game Kit
Unity Technologies
★★★★
Free Download