Bythëdosi (also Bitidosi, Bitadosi; Cyrillic: Битидоси, Битадоси) was a historical noble Albanian tribe (fis) in the Middle Ages. They inhabited the Cem valley in the Brda (Montenegro) area in south-eastern Montenegro, north-east of Podgorica.

Bytadosi derive their name from their oldest known patrilineal ancestor, Bytados (Cyrillic: Бись Дось), recorded in the Dečani chrysobulls among the inhabitants of the Albanian (arbanas) katun (pastoral community) of Liesh Tuzi in 1330.

The name Bytados is a compound of two Albanian words: bythë, meaning "buttocks", and dosë, "pig": in Latin, podex porci. The name probably originated as a nickname that was accepted by the progenitor of the Bytadosi tribe. It was a common custom among Albanians to give their tribal chiefs vulgar nicknames. Another example of such a tradition is the Epirote tribe of Losha, whose name originated as a vulgar nickname from the Albanian word for pockmark-lios.

The use of "bythë" (butt) in nicknames appears in both Arbëresh and medieval Albanian naming traditions, suggesting deep historical roots. Names like Bithacakëla, Bithëzeza, Butharragat among the Arbëresh show a consistent pattern, likely descriptive or humorous in origin. Their presence in Arbëresh communities, who migrated in the 15th century, confirms this as an old Albanian custom.

The presence of vulgar names such as Svinoglav (Albanian: Kryethi) and Kryezezi (literally blackhead) among medieval Albanians suggests that such a tradition was common.

They appear in historical record for the first time in 1330 in the Dečani chrysobulls as part of the Albanian (arbanas) katun (pastoral community) of Llesh Tuzi, that was situated somewhere around the medieval Župa (county) of Kuševo in Upper Zeta. Among the recorded inhabitants of the katun was a certain Bytados (Cyrillic: Бись Дось), who is most likely the progenitor of the Bythadosi clan. This katun included many communities that later formed their own separate communities: Mataguzi and his brothers, Reçi and his sons, Bushati and his sons, Pjetër Suma (ancestor of Gruda) and Pjetër Kuçi, first known ancestor of Kuči.

Another member of the Bytadosi clan, Pal Bitidosi (Cyrillic: Пав'ль Боусадоса), is mentioned in the Chrysobulls among the inhabitants of Kuševo, probably the son of Bytados from the katun. He later appears in Venetian records from 1335 as Paulus Busadosa, the leader of the Bytadosi (spelled in Venetian archives as Bisdos, Butadossi, Bitidossi, Busadossa) tribe.

Bytadosi settled the right bank of the Cem valley in medieval Upper Zeta (modern-day Montenegro) where they became a semi-independent community (katun or fis) and warrior band (ratnička družina) based on kinship ties of the same paternal ancestry. Since they were a powerful clan, they would often change oaths to various lords in their favor. Though originally vassals of Balšići, they would often side with the Venetians when it was in their favor.