Victor Adler (24 June 1852 – 11 November 1918) was an Austrian politician, a leader of the labour movement and founder of the Social Democratic Workers' Party (SDAP).

However, Schönerer's increasingly antisemitic policies, culminating in the amendment of an Aryan paragraph, led to an estrangement with Adler, who focussed on social issues.

Adler, a both moderate and charismatic social democrat, was able to unite the Austrian labour movement under his leadership, fighting against the anti-socialist laws implemented by the Cisleithanian government of Minister President Eduard Taaffe in 1884.

As a member of the Imperial Council parliament from 1905, he played a leading role in the fight for universal suffrage, finally achieved under Minister President Max Wladimir von Beck in 1906, whereafter the Social Democrats emerged as winner from the 1907 Cisleithanian legislative election.

An active supporter of the Second International, Adler tried to maintain the unity of the Austrian Social Democrats beyond ethnic conflicts and backed the idea of the United States of Greater Austria replacing the Dual Monarchy[citation needed].