Stephen Tomašević (died on May 25 1463) is the last sovereign from the Bosnian Kotromanić dynasty.

His father, King Stephen Thomas, arranges for him to marry Maria of Serbia and become Despot of Serbia in April 1459.

The marriage is meant to unite Bosnia and Serbia in their fight against the expanding Ottoman Empire, but fails in this regard.

After ruling Serbia for merely two months, Stephen Tomašević surrenders it to the Ottomans and flees back to his father's court.

Upon his father's death in 1461, Stephen Tomašević ascends as King of Bosnia, a kingdom whose existence is being increasingly threatened by the Ottomans.

He desperately tries to secure help from Pope Pius II, King Matthias Corvinus of Hungary and monarchs of other neighboring countries.

Confident that they will come to his aid, Stephen Tomašević refuses to deliver the customary tribute to Sultan Mehmed the Conqueror and thus provokes the invasion that costs him his life.

In 1463, Mehmed marches into Bosnia, meeting little effective resistance, and captures Stephen Tomašević, who is then beheaded.

The execution marks the fall of the Kingdom of Bosnia to the Ottoman Empire.