Light Higgs triplets in extra dimensions

We discuss the possibility that the Higgs triplet can be light (1 TeV in the most interesting case) without contradictions with the proton stability in the context of higher-dimensional theory. The proton stability is ensured by the suppression of Yukawa coupling of the Higgs triplet to the matter through its small overlap of wave functions in extra dimensions. The light Higgs triplets might be detected in future collider experiments as an alternative signature of GUT instead of the proton decay. The gauge coupling unification can be preserved by introducing extra bulk matter fields.