What is this called?

[Aqualoon]

Drawing a blank on this and it's driving me crazy, came up in conversation this morning and now I can't stop thinking about it.

It's the " ' " when it's over a letter, seen often when writing something in Spanish.

Anyone?

 

[Dustonthecabnit]

just refer to as an accent mark. If you use the 'proper name' people will not know what you mean and the ones that do will think your trying to be snotty.
this comes up alot here in TEJAS

 

[Reefscape]

Yup..accent mark, or here in UK we refer too it as an apostrophe

 

[deeda]

It's an acute accent mark.