Christiania Bank og Kreditkasse, branded domestically as Kreditkassen or K-Bank and internationally as Christiania Bank+ was a Norwegian bank that existed between 1848 and 2000 when it merged with MeritaNordbanken and became Nordea.

Christiania Bank had branch offices in London, New York, and Singapore.

It opened branches in 1897, under the directorship of Peter Harboe Castberg The bank expanded out of Oslo in 1957 when it bought Elverum Kreditbank and Hamar Privatbank, and in 1959 with the acquisition of Agder Bank.

In the last years of the 1980s, there was a major financial crisis in Norway and by 1991 the bank had used up all capital.

In 1995, the government reduced its ownership to 51%, listing it on the Oslo Stock Exchange, and in 1999 to 35%.