ER or Er may refer to:
Ernest Rutherford, 1st Baron Rutherford of Nelson, OM, FRS (30 August 1871 – 19 October 1937) was a New Zealand-born British physicist who came to be known as the father of nuclear physics.
Ernest Miller Hemingway (July 21, 1899 – July 2, 1961) was an American novelist, short story writer, and journalist.
Eric Patrick Clapton, CBE (born 30 March 1945), is an English rock and blues guitarist, singer, and songwriter.
Eritrea ( or ; Tigrinya: ኤርትራ?, listen ), officially the State of Eritrea, is a country in the Horn of Africa, with its capital at Asmara.
The Erie Canal is a canal in New York that is part of the east–west, cross-state route of the New York State Canal System (formerly known as the New York State Barge Canal).
EY (formerly Ernst & Young) is a multinational professional services firm headquartered in London, England.
In earth science, erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth's crust, then transport it away to another location.