Euripides was a tragedian of classical Athens. Along with Aeschylus and Sophocles, he is one of the three ancient Greek tragedians for whom any plays have survived in full. Of the around 95 plays attributed to him, 18 or 19 have survived almost completely partly because his popularity grew over time compared to Sophocles and Aeschylus.
The play Hippolytus is based on the myth of Hippolytus, son of Theseus, and how the meddling of the gods and a series of misunderstandings resulted in the death of him and his step-mother, Phaedra.
The Bacchae is considered one of Euripides's greatest tragedies. The story is based on the myth of King Pentheus of Thebes and his mother Agave, who are punished by the god Dionysus (also known to the Greeks as Bacchus) for refusing to worship him.
For Hippolytus, the 1 Cambridge University Press version is an easy-to-follow translation and comes with lots of background and commentary for the interested reader. For Bacchae, the 2 Hackett version translated by Paul Woodruff is easy to read, has comprehensive notes, and has a helpful introduction that presents various interpretations of the play. The translation by Pulitzer Prize-winning poet 4 C.K. Williams is also highly rated and captures the tragedy beautifully. Finally, poet Robin Robertson has done a 3 newer translation that has gotten great reviews. Either of these editions will serve you well.