Oracle user created information
DBA_USERS (Table) will give you access to WHEN your user was created, but AFAIK the only way to get WHO created your user is if auditing is turned on.

This also requires you to have access to the DBA_AUDIT_TRAIL table.

SELECT OS_USERNAME,
   USERNAME AS USER_WHO_CREATED_YOU,
   USERHOST,
   TERMINAL,
   TIMESTAMP,
   OBJ_NAME AS USER_CREATED,
   ACTION_NAME
 FROM DBA_AUDIT_TRAIL
 WHERE 
TIMESTAMP &gt; SYSDATE-90
AND ACTION_NAME ='CREATE USER'
--AND OBJ_NAME = 'YOURUSERNAMEGOESHERE'


Further Reading: https://docs.oracle.com/cd/B19306_01/server.102/b14237/statviews_3056.htm#i1619732