SPOILER: Mr. TerrificNews
Echo Kellum just confirmed in interview that he has indeed left the series. Hate to say it but I don't think I'm going to miss him that much. Just didn't care for the way they portrayed the character. He always seemed to be the member of the team who was there to be rescued.
https://deadline.com/2019/02/arrow-echo-kellum-exits-cast-series-regular-curtis-mr-terrific-1202555576/