1) Celtic mythology encompasses the folklore and legends of the Celtic peoples across Europe, particularly in regions like Ireland, Scotland, and Wales. It features deities like Morrigan, Cernunnos, and Brigid, and delves into themes of nature, magic, and the heroic exploits of legendary figures like Cu Chulainn.

2) Beyoncé, full name Beyoncé Giselle Knowles-Carter, is a highly influential American singer, songwriter, actress, and businesswoman. She rose to fame as a member of the group Destiny's Child and has since achieved success as a solo artist.

3) The Boston Celtics and the Los Angeles Lakers are the most successful teams in NBA history, with a combined total of 33 championships.

4) The process of impeachment involves charging a public official, such as a president or high-ranking government official, with misconduct and potentially removing them from office through a trial and vote by the legislature.