The bulk of the Greek displays are the Elgin Marbles, the portions of the Parthenon that was brought to England in 1806-1810 by Lord Elgin.
One section (south metope XXXI) depicts a centaur and a man engaged in battle.

A couple of other images from this section:
a Lycian Nereid Monument (in Ionian style) and a discus thrower (in the stairwell).