X
XA-4, Curtiss
XA-13, Northrop
XA-14 Shrike, Curtiss
XA-16, Northrop
XA-43, Curtiss
XB-15, Boeing
Xenophon (431-c.348 BC)
Xerxes I (r.486-465 BC)
Xerxes II (r.425-424 BC)
XF5B-1, Boeing XF5B (Model 205)
XF6B/ XBFB, Boeing (Model 236)
XF7B, Boeing
XF8B, Boeing
XHB-1 Cyclops, Huff-Daland
XHB-2, Atlantic
XHB-3, Huff-Daland
Xiang Yu, 232-202 BC
Xingyang, siege of, 204 BC
Xiphos
XLB-3, Huff-Daland
XLB-3A, Keystone
XLB-5, Huff-Daland
XLB-12, Keystone
XP-4, Boeing (Model 58)
XP-7, Boeing (Model 93)
XP-8, Boeing (Model 66)
XP-9, Boeing
XP-15, Boeing (Model 202)
XP-32, Boeing (Model 278A)
XP-37, Curtiss
XP-41, Seversky
XP-44 Rocket, Republic
XP-46, Curtiss
XP-52, Bell (Model 16)
XP-53, Curtiss
XP-59, Bell (Model 16)
XP-60, Curtiss
XP-72, Republic
XP-77, Bell
XP2M, Martin
XPY Admiral, Consolidated
XTBU-1 Sea Wolf, Chance-Vought