Unicode: 2500. Alias: Esc hline Esc. Letter-like form. Extensible character. Thickness can be adjusted using the SpanThickness option in StyleBox.
Unicode: 224E. Infix similarity operator. x ≎ y is by default interpreted as HumpDownHump[x,y]. Used to indicate geometrical equivalence.
Unicode: 00ED. Alias: Esc i' Esc. Letter. Included in ISO Latin-1.
Unicode: 00EF. Alias: Esc i" Esc. Letter. Included in ISO Latin-1.
Unicode: 00EC. Alias: Esc i` Esc. Letter. Included in ISO Latin-1.
\[IHat]
(Mathematica Character Name) Unicode: 00EE. Alias: Esc i^ Esc. Letter. Included in ISO Latin-1.
\[Iota]
(Mathematica Character Name) Unicode: 03B9. Aliases: Esc i Esc, Esc iota Esc. Greek letter. Not commonly used. Used in set theory to indicate an explicitly constructible set.
Unicode: 03BA. Aliases: Esc k Esc, Esc kappa Esc. Greek letter.
Unicode: 03BB. Aliases: Esc l Esc, Esc lambda Esc. Greek letter. Used in TraditionalForm for ModularLambda.
Unicode: 21E4. Infix arrow operator. x ⇤ y is by default interpreted as LeftArrowBar[x,y]. Sometimes used to indicate a backtab. Extensible character.