Macedonian leader, was born at Shtip in central Macedonia. As a youth he took part in the comitadji campaign against Turkey, becoming one of the most prominent leaders of the Bulgarian bands in Macedonia. After the treaties which concluded World War I had allotted his native district to Yugoslavia he went to Sofia and began to reorganize the old IMRO (Internal Macedonian Revolutionary Organization) against Yugoslavia and Greece.

Imprisoned by Stamboliski, he escaped through the connivance of his friends, retired to the mountains near Petritch and there organized a power which was able not only to terrorize Serbian and Greek Macedonia but also to defy the Bulgarian government, against which he declared irrevocable hostility in 1923 after he had failed to persuade Stamboliski to support his cause.

Alexandrov himself aimed at an autonomous Macedonia, with its capital at Salonika, and thus incurred the hostility of the more moderate group of "Federalists", who were on tolerable relations with the Yugoslav government. He helped to bring about the fall and death of Stamboliski in June 1923, and under the government of Tsankov was practically an independent ruler; but when this government also disavowed the Macedonians, Alexandrov turned elsewhere for help, and entered into relations, first with Turkey, then with Stjepan Radic, the Croat leader, and finally with the third International. A treaty concluded in the summer of 1924 between the Macedonian autonomists and the third International was alleged to bear Alexandrov's signature but afterward was repudiated by him. Violent dissension broke out in his party over the advisability or not of accepting Russian help and, as a result of them, Alexandrov was murdered on August 31, 1924.

Alexandrov was for years the uncrowned and absolute king of the Bulgarian Macedonians, who almost worshipped him. He was a very fine figure, tall, black-bearded and handsome, and as ruthless as he was brave. His courts knew only three verdicts: acquittal, 100 stripes or death, the last being inflicted for theft, insult to a woman or political treachery. He must have been responsible for many hundreds of deaths; withal, he was a man of personal probity and fanatical and selfless patriotism.