|Date of birth|
|Awards||Knight Grand Cross of the Royal Victorian Order|
|Education||University of Vienna|
|Political party||Ethiopian Democratic Unity Party|
Le'ul Ras Mengesha Seyoum (Ge'ez: መንገሻ ሰዩም) GCVO (born 7 December 1927) is a member of the imperial family of the Ethiopian Empire. In 1974, the monarchy was abolished by the Derg, a communist military junta.
Le'ul Dejazmach Mangasha Seyum was born in 1927 in Dengolat, a village in Enderta district, part of Tigray province of Ethiopia. He is the son of Ras Seyum Mangasha, the grandson of Ras Mangasha Yohannes, and the great grandson of Emperor Johannes IV. Yohannes IV was the only Emperor of the Tigrayan cadet branch of the Solomonic dynasty (being descended in female lines from Emperors Yohannes I and Eyasu I). Emperor Menelik II of Shoa came to power after the Battle of Metemma when Yohannes IV was killed and the male line of the Solomonic Dynasty was re-established on the Imperial throne. Mangasha Seyum is the heir to the Tigrean royal line and a rival to the Shoan emperor. Ras Mangasha Seyum's grandfather, Mangasha Yohannes was raised as the nephew of Yohannes IV. However Yohannes IV announced on his deathbed that Mangasha was his "natural" son and designated heir. It is still disputed among Tigrean royal descendants whether Mangasha Yohannes was indeed an actual son of Yohannes IV, or a nephew that Yohannes adopted on his deathbed in order to name him as his successor as his legitimate son Ras Araya Selassie Yohannes had died previously. There was a long-standing rivalry between the descendants of Ras Araya Selassie and Ras Mangasha Yohannes over the rule of Tigray and precedence. Her mother was Princess Adada (second wife of his father).
With the title of Leul Dejazmach Mengesha Seyoum was Governor of Arusi from 1952 to 1955. He was Governor of Sidamo from 1955 to 1958. In January 1949, Mangasha Seyum married one of Haile Selassie I's granddaughters, Princess Aida Desta. They are the parents of five sons Lij Michael Sehul, Lij Yohannes, Lij Stephanos, Lij Jalye, Lij Seyoum and a daughter Immabet Menen. Mengesha Seyum was also the father of the late Immabet Rebka from his first marriage to Abonesh Demisse cousin of Princess Atsede Asfaw who was also Mengesha Seyum's stepmother. After his father was murdered during the unsuccessful 1960 coup against Emperor Haile Selassie, Mengesha Seyoum was elevated to the title of Leul Ras and became Prince and Governor of Tigray. He governed from his capital in Mek'ele and held this position until 1974 when the monarchy was abolished.
On 1 February 1965, he was awarded the Knight Grand Cross of the Royal Victorian Order (GCVO) by Queen Elizabeth II of the United Kingdom.
In October 1974, after the monarchy was toppled, representatives of the Derg ordered Seyum Mangasha to the capital to face charges of corruption, but instead he fled to the hills. There Mengesha Seyoum helped to found a group that eventually became the Ethiopian Democratic Union (EDU). His wife, Princess Aida Desta, and his daughter were arrested by the Derg in 1974. Although his daughter would eventually escape abroad, his wife remained in prison for 14 years. The EDU was a conservative and pro-monarchy and is the oldest of the Ethiopian political parties. The EDU later merged with the Ethiopian Democratic Party and formed the Ethiopian Democratic Unity Party (EDUP), which later was one of the parties that joined to form the United Ethiopian Democratic Forces, one of the two largest opposition parties in Ethiopia. In 2000, the EDU reorganized in Addis Ababa as a legal opposition party after the Tigrayan People's Liberation Front led the Ethiopian People's Revolutionary Democratic Front to power. Leul Ras Mengesha has retreated from all involvement in the political affairs of this party and its successor organizations.
Leul Ras Mengesha Seyoum lives partly in Addis Ababa, and partly in the Washington D.C. area of the USA. His wife of more than 60 years, Princess Aida died on January 15, 2013 in Alexandria Virginia. He maintains a close relationship with his, children, nine grandchildren and three great-grandchildren. He is regarded as the senior surviving nobleman of the Ethiopian Empire, and the senior Prince of a cadet branch of the Imperial dynasty. Although for a significant period during the 1970s and 1980s he was regarded as a possible candidate for the succession by many monarchists, in 1989 he accepted and recognized the proclamation of Crown Prince Asfaw Wossen as Emperor in Exile of Ethiopia under the name Amha Selassie. Leul Ras Mengesha was prominent at the funerals of Emperor in Exile Amha Selassie, the reburial of Emperor Haile Selassie, Princess Tenagnework (who was his mother-in-law) and Empress Medferiashwork. With the death of Emperor Amha Selassie, Leul Ras Mengesha is considered the elder member of the extended Imperial family, and at public events where members of the Imperial family appear, such as royal funerals, is given precedence over all male members of the family except Crown Prince Zera Yacob Amha Selassie.
- Knight Grand Cordon of the Order of the Holy Trinity.
- Knight Grand Cross of the Royal Victorian Order (United Kingdom, 01/02/1965).