Ioannis (Yianis) Passalidis (Greek: Ιωάννης Πασαλίδης; 1886–1968) was a prominent member of the Greek Left and founder of the United Democratic Left party.

He then specialised as a surgeon in Odessa, taking the position of the director of the hospital of Sukhumi.

In July 1951 he was the one who induced the formation of the United Democratic Left (EDA), which he led until 1967, when the colonels' regime persecuted its members.

Passalidis took part in all the Greek legislative elections from 1952 to 1964 as the leader of the United Democratic Left, being among the protagonists of almost all the debates during this period in the parliament.

He is still remembered fondly among Greek leftists, who still refer to him as "Barbayiannis" (uncle John).