Tosia Altman[a] (Hebrew: טוסיה אלטמן; 24 August 1919 – 26 May 1943) was a courier and smuggler for Hashomer Hatzair and the Jewish Combat Organization (ŻOB) during the German occupation of Poland and the Warsaw Ghetto Uprising.

Volunteering as a courier, she passed herself off as a Polish gentile and risked her life to visit ghettos, first to organize underground education and later to warn them of the impending mass extermination of Jews.

[4][5]: 21  Influenced by her father's General Zionist convictions, Altman studied at a Hebrew-language gymnasium and joined the Hashomer Hatzair youth movement at the age of eleven.

Inspired to immigrate to Israel, she joined a training kibbutz in Częstochowa in 1938, but Hashomer Hatzair soon appointed her to the central leadership of youth education in Warsaw.

[4] Upon the invasion of Poland by Nazi Germany in September 1939, the Zionist youth movements urged their members to flee eastward to avoid the Germans.

When the Soviet Union invaded, Altman and the youth movement leadership evacuated to Vilna,[4] under Polish and then Lithuanian control until June 1940.

[7] Altman joined the headquarters of Hashomer Hatzair in Vilna, and helped to organize several unsuccessful attempts to send members of the youth movements illegally to Palestine.

[9] After two failed attempts to cross the Soviet and German borders, in December 1939 she visited her family in Włocławek and returned to Warsaw, the first youth movement leader to do so.

[5]: 89 On 24 December 1941, Altman and Haika Grossman managed to return to the Vilna Ghetto, where they met with Abba Kovner and the leadership of the United Partisan Organization.

[c] On her trip back to Warsaw, Altman visited several eastern Polish ghettos, including Grodno, to pass along this message.

[4] Upon her return to Warsaw, Altman found that the Jews were unwilling to accept that they were about to be exterminated, even after reports arrived of a death camp at Chełmno.

In July, during the Grossaktion Warsaw and after the establishment of the Jewish Combat Organization (ŻOB), Altman, due to her Aryan appearance and Polish language skills, was appointed a liaison with the Home Army and Armia Ludowa.

Altman was joined by Arie Wilner, another Hashomer Hatzair activist, in an attempt to convince the Polish resistance groups to arm them.

[12] After the January skirmish, the Home Army began to support the ŻOB in earnest, and the remaining Jews trained and built bunkers in preparation for the final liquidation.