GNU FreeFont
Unicode combining diacritics

Range U+0300-U+036F

Combining Diacritical Marks
̀́̂̃̄̅̆̇̈̉̊̋̌̍̎̏
̛̖̗̘̙̜̝̞̟̐̑̒̓̔̕̚
̡̢̧̨̠̣̤̥̦̩̪̫̬̭̮̯
̴̵̶̷̸̰̱̲̳̹̺̻̼̽̾̿
͇͈͉͍͎̀́͂̓̈́͆͊͋͌ͅ͏
͓͔͕͖͙͚͐͑͒͗͛͘͜͟͝͞
ͣͤͥͦͧͨͩͪͫͬͭͮͯ͢͠͡

Range U+1DC0-U+0DFF

Combining Diacritical Marks Supplement
᷎᷂᷊᷏᷀᷁᷃᷄᷅᷆᷇᷈᷉᷋᷌᷍
᷐᷑᷒ᷓᷔᷕᷖᷗᷘᷙᷚᷛᷜᷝᷞᷟ
ᷠᷡᷢᷣᷤᷥᷦ         
            ᷽᷿᷾᷼

When one of these follows another character, it is placed on that character. The font specifies automatic mark placement for many characters so that font rendering software can place the mark properly (but this specification has to be recognized by that software).

Note that not all combinations of letters with diacritcs make sense in any written language.

ò ó ô õ ō o̅ ŏ ȯ ö ỏ o̊ ő ǒ o̍ o̎ ȍ
o̐ ȏ o̒ o̓ o̔ o̕ o̖ o̗ o̘ o̙ o̚ ơ o̜ o̝ o̞ o̟
o̠ o̡ o̢ ọ o̤ o̥ o̦ o̧ ǫ o̩ o̪ o̫ o̬ o̭ o̮ o̯
o̰ o̱ o̲ o̳ o̴ o̵ o̶ o̷ o̸ o̹ o̺ o̻ o̼ o̽ o̾ o̿
ò ó o͂ o̓ ö́ oͅ o͆ o͇ o͈ o͉ o͊ o͋ o͌ o͍ o͎ o͏
o͐ o͑ o͒ o͓ o͔ o͕ o͖ o͗ o͘ o͙ o͚ o͛
o͜a o͝a o͞a o͟a o͠a o͡a o͢a
oͣ oͤ oͥ oͦ oͧ oͨ oͩ oͪ oͫ oͬ oͭ oͮ oͯ

The dot over i and j is removed for several marks, by a different mechanism, prior to the mark being placed over the dotless version of the letter.

ì í î ĩ ī i̅ ĭ i̇ ï ỉ i̊ i̋ ǐ i̍ i̎ ȉ
i̐ ȋ i̒ i̓ i̔ i̕ i̖ i̗ i̘ i̙ i̚ i̛ i̜ i̝ i̞ i̟
i̠ i̡ i̢ ị i̤ i̥ i̦ i̧ į i̩ i̪ i̫ i̬ i̭ i̮ i̯
ḭ i̱ i̲ i̳ i̴ i̵ i̶ i̷ i̸ i̹ i̺ i̻ i̼ i̽ i̾ i̿
ì í i͂ i̓ ḯ iͅ i͆ i͇ i͈ i͉ i͊ i͋ i͌ i͍ i͎ i͏
i͐ i͑ i͒ i͓ i͔ i͕ i͖ i͗ i͘ i͙ i͚ i͛
i͜a i͝a i͞a i͟a i͠a i͡a i͢a
iͣ iͤ iͥ iͦ iͧ iͨ iͩ iͪ iͫ iͬ iͭ iͮ iͯ

Ẁ Ẃ Ŵ W̃ W̄ W̅ W̆ Ẇ Ẅ W̉ W̊ W̋ W̌ W̍ W̎ W̏
W̐ W̑ W̒ W̓ W̔ W̕ W̖ W̗ W̘ W̙ W̚ W̛ W̜ W̝ W̞ W̟
W̠ W̡ W̢ Ẉ W̤ W̥ W̦ W̧ W̨ W̩ W̪ W̫ W̬ W̭ W̮ W̯
W̰ W̱ W̲ W̳ W̴ W̵ W̶ W̷ W̸ W̹ W̺ W̻ W̼ W̽ W̾ W̿
Ẁ Ẃ W͂ W̓ Ẅ́ Wͅ W͆ W͇ W͈ W͉ W͊ W͋ W͌ W͍ W͎ W͏
W͐ W͑ W͒ W͓ W͔ W͕ W͖ W͗ W͘ W͙ W͚ W͛
W͜a W͝a W͞a W͟a W͠a W͡a W͢a
Wͣ Wͤ Wͥ Wͦ Wͧ Wͨ Wͩ Wͪ Wͫ Wͬ Wͭ Wͮ Wͯ

The ogonek is applied to vowels in Polish and Lithuanian, as well as in several North American languages.

ą ę į ǫ ų y̨ Ą Ę Į Ǫ Ų Y̨ Ą̊ ą̊ ǭ

See Unicode FAQ on Characters and Combining Marks