Wikipedia:Naming conventions (Vietnamese)

Short forms
Vietnamese personal names are usually three syllables long, but may also be two or four syllables. The first syllable is the family name or surname. Because certain family names, notably Nguyen, are extremely common, they cannot be used to distinguish among individuals in the manner customary in English. Do not shorten two-syllable names, i.e. Lê Duẩn is always Lê Duẩn. For three-syllable names, use the final syllable as a short form to refer to the subject after the first reference. Thus Ngô Bảo Châu is shortened to "Châu". For four-syllable names, use the last two syllables as the short form. Thus Nguyễn Thị Minh Khai is "Minh Khai". It should be noted that "Hồ Chí Minh" is exception to these rules since this is a pseudonym with a strongly literal meaning. Chí Minh means "he who enlightens," so these two syllables are not divided. An explanatory header, Family name hatnote, may be used if clarification is considered necessary.

Monarchs
Vietnamese monarchs were variously referred to as kings (vua or vương) or emperors (hoàng đế). For the period prior to ascending the throne, refer to them by given name. A reigning monarch generally had both a temple name and an era name. Refer to the monarchs of the Nguyễn Dynasty (1802-1945) by era name, but to earlier monarchs by temple name. See List of Vietnamese monarchs for individual monarchs. (Note that "Dynasty" is (currently) capitalised in article titles Trần Dynasty but may not be in sources or in article copy).

The use and transliteration of Sino-Vietnamese characters
Until the 1920s, Vietnamese generally wrote using characters of Chinese origin. These could be used to write either classical Chinese (known as chữ nho Confucian characters), which had official status, or a vernacular script called chữ Nôm, which used the characters phonetically. If the primary source material gives a name in non-Latin characters, provide this form as a gloss. For example, the article on Lê Quý Đôn opens, "Lê Quý Đôn (1726–1784)". In this example, the markup  Lê Quý Đôn (1726–1784)  was used. This markup allows the reader to click an individual character to obtain additional information about it. Provide a character gloss only once in an article, either at the beginning or in a section entitled "Names". Chinese characters lost their official status in 1918. To provide a character gloss for a modern Vietnamese name is inappropriate as this practice misrepresents Chinese script as a form of modern Vietnamese.

Use of diacritics in personal names
Relevant discussions include RMs at Talk:Dục Đức, Talk:Lê Quý Đôn, Talk:Lê Thái Tông, Talk:Minh Mạng, Talk:Lady Triệu, Talk:Phan Bội Châu, Talk:Ngô Bảo Châu, Talk:Trần Văn Trà, Talk:Mỹ Linh, names at Talk:Đông Du, Talk:Trịnh Công Sơn, Talk:Võ Chí Công, Talk:Đặng Hữu Phúc, Talk:Lê Đức Thọ, Talk:Võ Nguyên Giáp, etc.

Geographic names
Province and District are (currently) capitalised in article titles, as Gia Bình District, but are often not capitalised in sources or article body.

Use of Sino-Vietnamese characters in geography articles
Use of Sino-Vietnamese characters (chữ Hán) in brackets in lead is only appropriate for articles on historical place names. Otherwise the name in chữ Hán characters should be given in brackets only where appropriate in the History section of a geographical article. See Vietnamese place names.

Use of Vietnamese diacritics in place names
Following VN DISTRICT NAMES RFC (August 2013) all districts and minor geographical names with no English exonym should be given in full Vietnamese font.

Chinese Domination
Earlier periods of the Chinese domination of Vietnam present possibilities for both Chinese and Vietnamese naming of places and people. Names given in Chinese characters by the primary sources may be transliterated either into pinyin (romanized Chinese) or into alphabetical Vietnamese. For example, can be transliterated either as Nányuè (Chinese pinyin) or as Nam Việt. Another example is Jiaozhi (article title in pinyin without Chinese tones) or Jiāozhǐ (pinyin) in Vietnamese Giao Chỉ. A consistent style should be used for a given article. Factors to consider include use by the source materials and whether the article has a Vietnamese or a Chinese orientation.