You will find below a list of accents with their corresponding html escape sequences. For example, to get the character u with an umlaut, "ü", type "ü". (Don't forget the ampersand at the beginning or the semicolon at the end of the escape sequence.) This table was modified for readability from an ISO Standard document.
CHARACTER HTML DESCRIPTION
á á small a, acute accent
Á Á capital A, acute accent
â â small a, circumflex accent
  capital A, circumflex accent
à à small a, grave accent
À À capital A, grave accent
å å small a, ring
Å Å capital A, ring
ã ã small a, tilde
à à capital A, tilde
ä ä small a, dieresis or umlaut mark
Ä Ä capital A, dieresis or umlaut mark
æ æ small ae diphthong (ligature)
Æ Æ capital AE diphthong (ligature)
ç ç small c, cedilla
Ç Ç capital C, cedilla
ð ð small eth, Icelandic
Ð Ð capital Eth, Icelandic
é é small e, acute accent
É É capital E, acute accent
ê ê small e, circumflex accent
Ê Ê capital E, circumflex accent
è è small e, grave accent
È È capital E, grave accent
ë ë small e, dieresis or umlaut mark
Ë Ë capital E, dieresis or umlaut mark
í í small i, acute accent
Í Í capital I, acute accent
î î small i, circumflex accent
Î Î capital I, circumflex accent
ì ì small i, grave accent
Ì Ì capital I, grave accent
ï ï small i, dieresis or umlaut mark
Ï Ï capital I, dieresis or umlaut mark
ñ ñ small n, tilde
Ñ Ñ capital N, tilde
ó ó small o, acute accent
Ó Ó capital O, acute accent
ô ô small o, circumflex accent
Ô Ô capital O, circumflex accent
ò ò small o, grave accent
Ò Ò capital O, grave accent
ø ø small o, slash
Ø Ø capital O, slash
õ õ small o, tilde
Õ Õ capital O, tilde
ö ö small o, dieresis or umlaut mark
Ö Ö capital O, dieresis or umlaut mark
ß ß small sharp s, German (sz ligature)
þ þ small thorn, Icelandic
Þ Þ capital THORN, Icelandic
ú ú small u, acute accent
Ú Ú capital U, acute accent
û û small u, circumflex accent
Û Û capital U, circumflex accent
ù ù small u, grave accent
Ù Ù capital U, grave accent
ü ü small u, dieresis or umlaut mark
Ü Ü capital U, dieresis or umlaut mark
ý ý small y, acute accent
Ý Ý capital Y, acute accent
ÿ ÿ small y, dieresis or umlaut mark