Quoc: As of May 17, 2018, 138 episodes of Arrow have aired, concluding the sixth season. On April 2, 2018, the CW renewed the series for a seventh season.

Answer this question based on the passage: when was the last episode of arrow aired?
HW Chung: OK, some thoughts:
The important part for answering this question is: As of May 17, 2018, 138 episodes of Arrow have aired, concluding the sixth season. The answer is May 17 , 2018.