▁films , ▁he ▁is ▁port rayed ▁by ▁Log an ▁L erman . ▁In ▁the ▁musical , ▁he ▁is ▁port rayed ▁by ▁Chris ▁Mc Car rell . ▁ ▁Gro ver ▁Under wood ▁Gro ver ▁Under wood ▁is ▁a ▁sat yr ▁and ▁Per cy ' s ▁best ▁friend . ▁He ▁appears ▁in ▁The ▁Light ning ▁Th ief , ▁The ▁Sea ▁of ▁Mon sters , ▁The ▁T itan ' s ▁Cur se , ▁The ▁Battle ▁of ▁the ▁Lab yr inth , ▁The ▁Last ▁Olymp ian , ▁The ▁Son ▁of ▁Ne pt une , ▁The ▁House ▁of ▁H ades , ▁The ▁Blood ▁of ▁Olymp us ▁and ▁The ▁Burn ing ▁Maz e . ▁ ▁He ▁has ▁cur ly ▁re dd ish - b rown ▁hair ▁and ▁fur , ▁ac ne , ▁and ▁a ▁wis py ▁go ate e . ▁His ▁horn s ▁grow ▁larger ▁as ▁the ▁series ▁progress es , ▁and ▁he ▁must ▁take ▁increasing ly ▁careful ▁measures ▁to ▁hide ▁them ▁and ▁his ▁go at ▁legs ▁while ▁pos ing ▁as ▁human . ▁In ▁The ▁Light ning ▁Th ief , ▁Ch ir on ▁states ▁that ▁Gro ver ▁is ▁small ▁even ▁for ▁his ▁age : ▁He ▁is ▁twenty - e ight ▁then , ▁but ▁because ▁a ▁sat yr ' s ▁lif es pan ▁is ▁twice ▁that ▁of ▁a ▁human , ▁he ▁is ▁considered ▁a ▁te en ager . ▁Gro ver ▁is ▁quite ▁sensitive ▁and ▁attached ▁to ▁nature . ▁A ▁veget arian , ▁he ▁is ▁known ▁to ▁eat ▁tin ▁can s , ▁furn iture , ▁and ▁wor ships ▁en ch il