Ras Kassa Hailu (Amharic: ካሣ ኀይሉ ዳርጌ; 7 August 1881 – 16 November 1956) was a Shewan Amhara nobleman, the son of Dejazmach Haile Wolde Kiros of Lasta, the ruling heir of Lasta's throne and younger brother of Emperor Tekle Giyorgis II, and Tisseme Darge, the daughter of Ras Darge Sahle Selassie, brother of Menelik II's father.

John Spencer, who advised Ras Kassa during the writing of the 1955 Constitution of Ethiopia, described him as "surely the most conservative of all the rases in constant attendance at the court."

Large, bearded and silent, this imposing dignitary wore a black cloak with gold clasps worked into the form of lion heads.

"[1] Although he had by birth a better claim to the throne than his younger cousin Ras Tafari (the later Emperor Haile Selassie I), Kassa valued loyalty over ambition, and was content with his fief of Selale province near the monastery of Debre Libanos.

[6] In early 1941, during the East African Campaign of World War II, Ras Kassa returned to Ethiopia with the Emperor and Gideon Force.