Stybba was given to Meriadoc Brandybuck by King Theoden. Stybba was a shaggy little grey pony. Merry was left behind in the battle at Pelennor Fields, and went with Eowyn, (Dernhelm in the battle) and had to leave the pony behind but rode Stybba back in the Shire.
Stybba= "Stump, small, stout"