Which philosopher drank hemlock after his trial in Athens?

Socrates, in 399 BC, convicted of impiety and corrupting the young by a jury of several hundred citizens. He could have proposed exile and was expected to; instead he suggested the city should reward him with free meals for life, which did not help, and the vote for death was larger than the vote to convict.

He wrote nothing. Everything comes from other people - Plato, who is a student building his own philosophy in his teacher's mouth; Xenophon, more literal and less interesting; and Aristophanes, who put him in a comedy as a ridiculous figure hanging in a basket. Separating the historical Socrates from Plato's character is a permanent scholarly problem with no solution.

The trial is usually read as free thought against an intolerant state, and the politics underneath it were sharper than that. Athens had recently lost a long war and endured a brutal oligarchy, and several of Socrates' close associates had been prominent in it - Critias led the Thirty Tyrants and Alcibiades had defected to Sparta. An amnesty prevented prosecuting anyone directly for the coup, and a charge of corrupting the young against the man who had taught them was a way around it.