Invisible Text

U+200B

Zero Width Space

Works in messages

U+200C

Zero Width Non-Joiner

Joins/breaks scripts

U+200D

Zero Width Joiner

Emoji joiner — visible effects

U+2060

Word Joiner

No-break joiner

U+FEFF

Byte Order Mark

Often stripped

U+3164

Hangul Filler

Classic blank nickname

U+115F

Hangul Choseong Filler

Blank nickname alt

U+2800

Braille Pattern Blank

Visible-ish blank cell

U+1D15

Musical Symbol Null

May not render