Required Fonts in Sierra

The minimum fonts recommended for Sierra in the /System/Library/Fonts/ folder are:

Apple Color Emoji.ttc
Avenir.ttc
Courier.dfont
Geneva.dfont
Helvetica.dfont
HelveticaNeue.dfont
HelveticaNeueDeskInterface.ttc
Keyboard.ttf
LastResort.ttf
LucidaGrande.ttc
Menlo.ttc
Monaco.dfont
PingFang.ttc
SFCompactDisplay-Black.otf
SFCompactDisplay-Bold.otf
SFCompactDisplay-Heavy.otf
SFCompactDisplay-Light.otf
SFCompactDisplay-Medium.otf
SFCompactDisplay-Regular.otf
SFCompactDisplay-Semibold.otf
SFCompactDisplay-Thin.otf
SFCompactDisplay-Ultralight.otf
SFCompactRounded-Black.otf
SFCompactRounded-Bold.otf
SFCompactRounded-Heavy.otf
SFCompactRounded-Light.otf
SFCompactRounded-Medium.otf
SFCompactRounded-Regular.otf
SFCompactRounded-Semibold.otf
SFCompactRounded-Thin.otf
SFCompactRounded-Ultralight.otf
SFCompactText-Bold.otf
SFCompactText-BoldItalic.otf
SFCompactText-Heavy.otf
SFCompactText-HeavyItalic.otf
SFCompactText-Light.otf
SFCompactText-LightItalic.otf
SFCompactText-Medium.otf
SFCompactText-MediumItalic.otf
SFCompactText-Regular.otf
SFCompactText-RegularItalic.otf
SFCompactText-Semibold.otf
SFCompactText-SemiboldItalic.otf
SFNSDisplay.ttf
SFNSDisplayCondensed-Black.otf
SFNSDisplayCondensed-Bold.otf
SFNSDisplayCondensed-Heavy.otf
SFNSDisplayCondensed-Light.otf
SFNSDisplayCondensed-Medium.otf
SFNSDisplayCondensed-Regular.otf
SFNSDisplayCondensed-Semibold.otf
SFNSDisplayCondensed-Thin.otf
SFNSDisplayCondensed-Ultralight.otf
SFNSText.ttf
SFNSTextCondensed-Bold.otf
SFNSTextCondensed-Heavy.otf
SFNSTextCondensed-Light.otf
SFNSTextCondensed-Medium.otf
SFNSTextCondensed-Regular.otf
SFNSTextCondensed-Semibold.otf
SFNSTextItalic.ttf
Symbol.ttf
Times.dfont

Recommended minimum fonts for the /Library/Fonts/ folder:

AppleGothic.ttf.
Arial.ttf
Arial Bold.ttf
Arial Italic.ttf
Arial Bold Italic.ttf
Arial Black.ttf
Arial Narrow.ttf
Arial Narrow Bold.ttf
Arial Narrow Italic.ttf
Arial Narrow Bold Italic.ttf
Comic Sans MS.ttf
Comic Sans MS Bold.ttf
Georgia.ttf
Georgia Italic.ttf
Georgia Bold.ttf
Georgia Bold Italic.ttf
Impact.ttf
Tahoma.ttf
Tahoma Bold.ttf
Times New Roman.ttf
Times New Roman Bold.ttf
Times New Roman Italic.ttf
Times New Roman Bold Italic.ttf
Trebuchet MS.ttf
Trebuchet MS Bold.ttf
Trebuchet MS Italic.ttf
Trebuchet MS Bold Italic.ttf
Verdana.ttf
Verdana Bold.ttf
Verdana Italic.ttf
Verdana Bold Italic.ttf
Wingdings.ttf
Wingdings 2.ttf
Wingdings 3.ttf
Webdings.ttf

Thank You Kurt Lang for constantly updating Us with your font knowledge!
http://www.jklstudios.com/misc/osxfonts.html#requiredfonts