G̃

Doulos SIL glyphs for Majuscule and minuscule g̃.

G̃ / g̃ is a letter which combines the common letter G with a tilde.

The letter does not exist in many alphabets. Examples of alphabets with this letter are:

Guarani alphabet – where the tilde marks nasalization of /g/, representing the sound /ŋ/
Filipino alphabet – during the Spanish colonial period and up to the mid-20th century, adopting Spanish orthography for the Tagalog language
Sumerian language – an extinct language, where it is used to transcribe the cuneiform script.
Northern Sámi orthography – g̃ appears in the Sámi alphabet used by Rask in Ræsonneret lappisk sproglære in 1832

The letter is also occasionally used as a (stylistic) substitute for Ğ in languages such as Turkish.

Computer encoding

Unicode encodes g with tilde with a combining diacritical mark (U+0303 ◌̃ COMBINING TILDE), rather than a precomposed character. As such, the tilde may not align properly with some typefaces and systems. Additionally, owing to the difficulties in inputting this character, Guarani speakers often replace it with g with circumflex (ĝ) or omit the diacritic altogether.^[1]

Letter	Unicode sequence	HTML
G̃	U+0047 U+0303	G ̃
g̃	U+0067 U+0303	g ̃

References

^ Redish, Laura; Lewis, Orrin. "Guarani Pronunciation and Spelling Guide". Native Languages of the Americas. Retrieved 16 September 2015. Most Guarani speakers don't use this character, instead spelling this sound the same as a plain g.