Constantin Ritter von Isopescu-Grecul (or cavaler de Isopescu-Grecul; first name also Konstantin, last name also Isopescul-Grecul, Isopescu Grecu; Ukrainian: ?????????? ??????????-???????; 1871–1938) was an Austro-Hungarian-born Romanian jurist, politician, and journalist.
He represented the region of Bukovina and a Romanian constituency in the Austrian House of Deputies continuously from 1907, participating in the political events of World War I.
He was foremost known as a legal reformer and a political moderate, who objected to radical forms of Romanian nationalism and mainly sought to obtain a special status for the Romanians within a reformed Austria.
His loyalism was rewarded by the Austrian authorities and antagonized the Romanian National People's Party, but Isopescu-Grecul also took distance from the pro-Austrian line advocated by Aurel Onciul.
In 1908, Isopescu-Grecul joined Nicu Flondor and Teofil Simionovici in creating an Independent Party, which espoused a moderate program.
He later rallied behind Iancu Flondor, embracing his conservative approach to national issues.
He was drawn closer to nationalism during the world war.
He denounced the persecution of Romanians in Transylvania, and was disappointed by Austria's offer to merge Bukovina into a Ukrainian People's Republic.
In late 1918, he still contemplated autonomy or independence for Bukovina and Transylvania, rather than union with the Kingdom of Romania, promoting Wilsonianism.
When public order broke down in Vienna, he and Iuliu Maniu organized defense units of Romanians from the Common Army, which doubled as a police force.
The process of union between Bukovina–Transylvania and Romania having been initiated, Isopescu-Grecul accepted the outcome.
He continued to serve as Romanian envoy in Vienna and Prague for most of the Hungarian–Romanian War, when he favored forging a long-lasting alliance between Romania and the Hungarian conservative forces.
In 1920, Isopescu-Grecul made his way back to Bukovina, an adviser of the Romanian governments and an investor in forestry businesses.
He made a return to politics eight years later, when he joined Maniu's National Peasants' Party and served briefly in the Chamber of Deputies.
In 1930–1933, he held the office of rector of Czernowitz University, an institution which he also represented in the Senate of Romania.