Can you explain the critical role of external auditors in company?

The role is an external auditor is very critical because as a well experienced third party , he will be able to interpret more the financial situation of the company by pointing at everything that is incorrect.

I agree with previous answers

The critical role of the external auditors is to preserve being independent in fact and in appearance.  Independence in fact means that there should absolutely no legal relationship between the external auditor and the auditee.  The owners of both the audit firm and the auditee company and their immediate family members have no business and personal relationship with each other.   Morever, both should avoid any doubt in the appearance of independence between the parties.  The external auditors should avoid receiving expensive gifts, asking for favor such as job recommendation for any of its staff, receiving hotel accomodation, or soliciting contributons from the clients.  These will impair the independence of the external auditor in appearance and place cloud of doubt in the mind of the public.  

The role of auditor most importantly involves examination of financial accounts and evaluation of financial controls implemented in the organization with the view to express an opinion on the financial statements wheather it gives true and fair view of the affairs of the company and also to detect errors or frauds if any in the financial accounting.