This paper establishes an analogue of Greibach’s hardest language theorem (“The hardest context-free language”, SIAM J. Comp., 1973) for the subfamily of LL languages. The first result is that there is a language L₀ defined by an LL(1) grammar in the Greibach normal form, to which every language L defined by an LL(1) grammar in the Greibach normal form can be reduced by a homomorphism, that is, w∈ L if and only if h(w) ∈ L₀. Then it is shown that this statement does not hold for LL(k) languages. The second hardest language theorem is then established in the following form: there is a language L₀ defined by an LL(1) grammar in the Greibach normal form, such that, for every language L defined by an LL(k) grammar, there exists a homomorphism h, for which w∈ L if and only if h(w$ ) ∈ L₀, where $ is a new symbol.