Clawdia Koopa is a character that is mentioned in one issue of Nintendo Power UK. Nothing is known of her except her name and that she is or was Bowser's wife. There is much controversy surrounding whether or not she actually exists, as the Nintendo Power reference may not have been meant to be taken seriously.
Many suspect she was the mother of Bowser's children, the Koopalings, however his youngest son, Bowser Jr. has no knowledge of her, instead believing Princess Peach to be his mother during the course of Super Mario Sunshine. This indicates she may have died when he was young, or never existed at all, though this still leaves the question of the origin of Bowser's offspring. The fact that Bowser considers his "marriage" to Princess Peach in Super Paper Mario legitimate also implies he no longer has or never had a wife.
-Source: http://www.mariowiki.com/Clawdia_Koopa#Clawdia_Koopa
