No Chico Hamilton yet? Disgraceful!
Tony Hateley and Willie Hamilton have been mentioned, so I'll go for Villa's second youngest ever player, Walter "Wally" Hazeldene, who made his debut against the Albion in November 1957, aged just 16. (Jimmy Brown became Villa's youngest ever player when he made his debut under Tommy Docherty in 1970, a few days short of his 16th birthday.)
A few more obscure "Hs": David Hunt, Steve Hunt and Tommy Hughes.
I'd mention Alan Hutton too, but I don't want to upset people!