Exhibit 15

ACKNOWLEDGMENT OF ERNST & YOUNG LLP,

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

November 1, 2017

The Board of Directors and Shareholders of KeyCorp

We are aware of the incorporation by reference in the following Registration Statements (including all amendments thereto) of KeyCorp:

Form S-3 No. 333-55959        

Form S-3 No. 333-59175        

Form S-3 No. 333-64601        

Form S-3 No. 333-76619        

Form S-3 No. 333-151608        

Form S-3 No. 333-174865        

Form S-3 No. 333-196641

Form S-3 No. 333-218629        

Form S-4 No. 333-146456        

Form S-8 No. 333-49609        

Form S-8 No. 333-70669        

Form S-8 No. 333-70703        

Form S-8 No. 333-70775        

Form S-8 No. 333-72189        

Form S-8 No. 333-92881        

Form S-8 No. 333-45320        

Form S-8 No. 333-45322        

Form S-8 No. 333-99493        

Form S-8 No. 333-107074        

Form S-8 No. 333-107075        

Form S-8 No. 333-107076        

Form S-8 No. 333-109273        

Form S-8 No. 333-112225        

Form S-8 No. 333-116120        

Form S-8 No. 333-167093        

Form S-8 No. 333-188703

Form S-8 No. 333-208272

of our review report dated November 1, 2017 relating to the unaudited consolidated interim financial statements of KeyCorp that are included in its Form 10-Q for the quarter ended September 30, 2017.

Ernst & Young

Cleveland, Ohio