Hi B kld,

Yes you are Right, Below are the prefix for all other object.

Entity                                                        Prefix
 
    ACCOUNT                         '001'
    QUOTE                           '0Q0'
    NOTE                            '002'
    CONTACT                         '003'
    USERS                           '005'
    OPPORTUNITY                     '006'
    ACTIVITY                        '007'
    OPPORTUNITY_HISTORY             '008'
    FORECAST_ITEM                   '00A'
    FILTER                          '00B'
    DELETE_EVENT                    '00C'
    ORGANIZATION                    '00D'
    USER_ROLE                       '00E'
    QUEUE                           '00G'
    GROUPS                          '00G'
    PARTNER                         '00I'
    OPPORTUNITY_COMPETITOR          '00J'
    OPPORTUNITY_CONTACT_ROLE        '00K'
    CUSTOM_FIELD_DEFINITION         '00N'
    REPORT                          '00O'
    ATTACHMENT                      '00P'
    LEAD                            '00Q'

Please check below post to check other object prefix also
https://help.salesforce.com/apex/HTViewSolution?urlname=Standard-Field-Record-ID-Prefix-Decoder&language=en_US (https://help.salesforce.com/apex/HTViewSolution?urlname=Standard-Field-Record-ID-Prefix-Decoder&language=en_US)

You can get prefix of any custom object by below code:-

Schema.DescribeSObjectResult r = CustomObject__c.sObjectType.getDescribe();
String keyPrefix = r.getKeyPrefix();
System.debug('Printing --'+keyPrefix );

you can try below code to get prefix:-

public class SchemaGlobalDescribe{
    public static String findObjectNameFromRecordIdPrefix(String recordIdOrPrefix){
        String objectName = '';
        try{
            //Get prefix from record ID
            //This assumes that you have passed at least 3 characters
            String myIdPrefix = String.valueOf(recordIdOrPrefix).substring(0,3);
             
            //Get schema information
            Map<String, Schema.SObjectType> gd =  Schema.getGlobalDescribe(); 
             
            //Loop through all the sObject types returned by Schema
            for(Schema.SObjectType stype : gd.values()){
                Schema.DescribeSObjectResult r = stype.getDescribe();
                String prefix = r.getKeyPrefix();
                System.debug('Prefix is ' + prefix);
                 
                //Check if the prefix matches with requested prefix
                if(prefix!=null && prefix.equals(myIdPrefix)){
                    objectName = r.getName();
                    System.debug('Object Name! ' + objectName);
                    break;
                }
            }
        }catch(Exception e){
            System.debug(e);
        }
        return objectName;
    }
}

Please below post for more detail.
https://help.salesforce.com/apex/HTViewSolution?urlname=How-to-find-Object-Type-from-Record-ID-Prefix&language=en_US (https://help.salesforce.com/apex/HTViewSolution?urlname=How-to-find-Object-Type-from-Record-ID-Prefix&language=en_US)

NOTE:- Prefix for standard object will be same in all org but custom object can be differnt. you can try below code to get custom object prefix.


Schema.DescribeSObjectResult r = CustomObject__c.sObjectType.getDescribe();
String keyPrefix = r.getKeyPrefix();
System.debug('Printing --'+keyPrefix );


Please mark this as solution if this will help you. So that if some one has same issue this post can help other also.

Thanks,
Amit Chaudhary