Depending upon the position of centromere, a chromosome may have the following shapes-

Telocentric : Rod shaped, having centromere at the proximal end.
Acrocentric : Rod-shaped, having centromere very close to one end but slightly below the proximal position.
Submetacentric : T-shaped or L-shaped, having centromere near the middle position.
Metacentric : 'V' shaped, having the centromere at the centre and chromatids forming two equal arms.