Table:
text: List of DC Comics characters: X
X
X
Name_ Original_Publisher First_Appearance Year_ Date_
X` Hal DC Comics The New Teen Titans , Vol. 1, #24 1982 October
X-21 DC Comics Action Comics , Vol. 1, #333 1966 February
X-24 DC Comics The New Titans , Vol. 1, #73 1991 February
X-2-Y DC Comics Action Comics , Vol. 1, #344 1966 December
X-5 Super Agent Quality Comics Hit Comics , Vol. 1, #1 1940 July
X Quality Comics Military Comics , Vol. 1, #1 1942 March
Xadu, Doctor DC Comics Adventure Comics , Vol. 1, #283 1961 April
Xanna Gorilla Comics / DC Comics Empire , Vol. 1, #1 2000 May

text: List of DC Comics characters: X
X
X
Name_ Original_Publisher First_Appearance Year_ Date_
Xenofobe DC Comics Superman , Vol. 1 #295 1976 January
Xeo DC Comics Detective Comics , Vol. 1. #260 1958 October
Xera DC Comics Legion of Super-Heroes , Vol. 3, #32 1987 March
Xero DC Comics Xero, Vol. 1, #1 1997 May
Xiang-Fa DC Comics Green Lantern , Vol. 3, #19 1991 December
Xiuhtecutli DC Comics Justice League International , Vol. 2, #63 1994 April
XL Terrestrial Warner Bros. Animation Teen Titans (TV series) 2004 August 28
Xola Aq DC Comics Adventure Comics , Vol. 1, #350 1966 November
Xolotl DC Comics 52 , Vol. 1, #21 2006 September
Xombi Milestone Media Xombi , Vol. 1, #0 1994 January

Question: What first appeared among DC Comics characters in the 1966 comic X-2-Y?