Common room located in the Gryffindor Tower. Access is behind the Fat Lady.
Common known members of the Gryffindor house:
Harry Potter, Albus Dumbledore, Ronald Weasley, Hermione Granger, Rubeus Hagrid, Neville Longbottom, Sirius Black, Remus Lupin, Ginny Weasley, Fred Weasley, George Weasley, Peter Pettigrew, Lily Evans, James Potter, Oliver Wood
Nearly Headless Nick is the ghost that represents the House of Gryffindor.