Unicode: 0009. Spacing character. Equivalent to the ordinary ASCII character with code 9. Can be entered in strings as ∖t.
Unicode: 007E. Raw operator. Equivalent to the ordinary ASCII character with code 126. In addition to one-dimensional uses, OverscriptBox[x, ~] is by default interpreted as ...
Unicode: 005F. Raw operator. Equivalent to the ordinary ASCII character with code 95. OverscriptBox[x, _] is interpreted as OverBar[x]. UnderscriptBox[x, _] is interpreted as ...
Unicode: 007C. Raw operator. Equivalent to the ordinary ASCII character with code 124. Extensible character.
Unicode: 2036. Alias: Esc `` Esc. Letter-like form.
Unicode: 220B. Alias: Esc mem Esc. Infix set relation operator. x ∋ y is by default interpreted as ReverseElement[x,y]. Not the same as \[SuchThat].
Unicode: 21CB. Infix arrow-like operator. x ⇋ y is by default interpreted as ReverseEquilibrium[x,y]. Extensible character.
Unicode: 2035. Alias: Esc ` Esc. Letter-like form. Used in an overscript position as a grave accent.
Unicode: 296F. Infix arrow-like operator. x ⥯ y is by default interpreted as ReverseUpEquilibrium[x,y]. Extensible character.
\[Rho]
(Mathematica Character Name) Unicode: 03C1. Aliases: Esc r Esc, Esc rho Esc. Greek letter.