Santeri Alkio (born Aleksander Filander; 17 June 1862 – 24 July 1930) was a Finnish politician, author and journalist.

Alkio was born in Laihia; his parents were Juho and Maria (née Jakku) Filander.

To keep the agrarian folk from becoming ensnared by socialism, he founded the Etelä-Pohjanmaan Nuorsuomalainen Maalaisliitto ("Young-Finnish Countrymens' Union of Southern Ostrobothnia"), which he later fused into the less ideological Maalaisväestön liitto ("Union of the Rural Population", later Centre Party of Finland).

Alkio became the chief ideologue of the Maalaisliitto, and is still considered the father of the party in spirit.

An ardent temperance-movement activist, he participated in drafting the Finnish Prohibition and also was the minister responsible for the confirmation of president K. J. Ståhlberg.

In 1906 Alkio wrote that "We want to liberate the beautiful and simple teachings of Jesus from the tyranny of theology and that is why we would like to withdraw the support of the state from one confession and to proclaim it to all."