Russian prima ballerina Natalia Bessmertnova has died after a long illness at the age of 66, the Bolshoi Theatre announced in Moscow.
Bessmertnova became a Bolshoi star in the Soviet period in 1961, marrying artistic director, Yuri Grigorovich, and later teaching in retirement.
Her husband gave her lead roles in his own productions, such as Spartacus.
In 1995, she took part in a historic strike at the Bolshoi over changes which prompted Grigorovich to resign.
Their refusal to perform Romeo and Juliet resulted in the first cancellation in more than 200 years of the company's history.
Bessmertnova died at a Moscow hospital after suffering from an unspecified grave illness, Bolshoi spokeswoman Yekaterina Novikova said.
Bolshoi director Anatoly Iksanov reacted by calling her death a "huge loss for the Bolshoi Theatre and for our whole culture".
She had been "the pride and glory of the company to which she devoted her entire life", he added.
Despite the strike of 1995, she returned to the Bolshoi in 2001-03 to teach, according to the company's website.
She won many Soviet prizes for her dancing, and is especially remembered for the part of Giselle.
She is survived by her husband.