Maternal aunt of the composer (b. 14/26 February 1805; d. 17/29 January 1882), born Yekaterina Andreyevna Assier (Екатерина Андреевна Ассиер); known after marriage as Yekaterina Andreyevna Alekseyeva (Екатерина Андреевна Алексеева).
Yekaterina was the eldest daughter of Andrey Assier and his wife Yekaterina. She was an amateur singer (contralto), who influenced Tchaikovsky's early musical development. She married Major-General Aleksandr Alekseyev (d. 1861), and they had a son, Ivan, who became an army officer.
Between May 1852 and April 1853 Tchaikovsky lived with his aunt Yekaterina at her apartment at 1 Kosoy Lane in Saint Petersburg.
Yekaterina Alekseyeva died on 17/29 January 1882, aged 76, and was buried at the Smolenskoye Cemetery in Saint Petersburg.
Correspondence with Tchaikovsky
One letter from Tchaikovsky to Yekaterina Alekseyeva has survived, dating from 1867, and has been translated into English on this website: