Unity unlit shaders with shadow and cutout – it can be useful:

Unlit shadow cast

Shader "UnlitShadows/UnlitShadowCast" {
Properties{ _MainTex("Base (RGB)", 2D) = "white" {} }
SubShader{ Pass{ SetTexture[_MainTex] } } FallBack "VertexLit" }

Unlit shadow cast cutout

Shader "UnlitShadows/UnlitShadowCastCutout" {
Properties{ _Color("Main Color", Color) = (1,1,1,1) _MainTex("Base (RGB)", 2D) = "white" {} _Cutoff("Cutout", Range(0,1)) = 0.5 }
SubShader{ Pass{ Alphatest Greater[_Cutoff] SetTexture[_MainTex] } } Fallback "Transparent/Cutout/VertexLit" }

Unlit shadow receive

Shader "UnlitShadows/UnlitShadowReceive" {
Properties{ _MainTex("Base (RGB)", 2D) = "white" {} }
SubShader{ Pass{ SetTexture[_MainTex] } Pass { Blend DstColor Zero Tags{ "LightMode" = "ForwardBase" }
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
#pragma multi_compile_fwdbase
#include "AutoLight.cginc"
struct v2f {
float4 pos : SV_POSITION; LIGHTING_COORDS(0,1) };
v2f vert(appdata_base v) {
v2f o; o.pos = mul(UNITY_MATRIX_MVP, v.vertex); TRANSFER_VERTEX_TO_FRAGMENT(o);
return o; }
fixed4 frag(v2f i) : COLOR{
float attenuation = LIGHT_ATTENUATION(i);
return attenuation;
} ENDCG } } Fallback "VertexLit" }

Unlit shadow receive cutout

Shader "UnlitShadows/UnlitShadowReceive" {
Properties{ _Color("Main Color", Color) = (1,1,1,1) _MainTex("Base (RGB)", 2D) = "white" {}	_Cutoff("Cutout", Range(0,1)) = 0.5 }
SubShader{ Pass{ Alphatest Greater[_Cutoff] SetTexture[_MainTex] }	Pass{ Blend DstColor Zero Tags{ "LightMode" = "ForwardBase" }
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
#pragma multi_compile_fwdbase
#include "AutoLight.cginc"
struct v2f {
float4 pos : SV_POSITION; LIGHTING_COORDS(0,1) };
v2f vert(appdata_base v) {
v2f o; o.pos = mul(UNITY_MATRIX_MVP, v.vertex); TRANSFER_VERTEX_TO_FRAGMENT(o);
return o; }
fixed4 frag(v2f i) : COLOR{
float attenuation = LIGHT_ATTENUATION(i);
return attenuation;
} ENDCG } } Fallback "Transparent/Cutout/VertexLit" }