Emilija Vileišiene née Jasmantaite (1861–1935) was a Lithuanian activist.
Born to a noble family, she attended the Smolny Institute and lived with her older brother in Saint Petersburg and Caucasus.
When her brother became severely ill, they moved to Vilnius (Wilno, Vilna) where Vileišiene met her husband Antanas Vileišis and became active in Lithuanian cultural life.
She was an active member of various Lithuanian organizations, including the Lithuanian Mutual Relief Society of Vilnius, Society of Saint Zita for servants, cultural Ruta Society.
During World War I, she was a board member of the Lithuanian Society for the Relief of War Sufferers and was particularly active in organizing relief for war refugees.
After the war, she remained in Vilnius and continued active public life despite several arrests by the Polish government.
In 1928–1930, she toured numerous Lithuanian American communities collecting donations for the orphans and the poor.