The noun 'Beatle' is a proper noun, the name of a famous singing group. A proper noun starts with a capital letter.
The possessive form for the noun Beatle is Beatle's.
Example: The Beatle's first hit single was "Love Me Do".
If you were thinking of the type of insect, a beetle, the singular possessive form is beetle's.
Example: The beetle's wings spread and it flew away.
The possessive form is Amos's.
The singular possessive form is herd's.
The singular possessive form is heart's; the plural possessive form is hearts'.
The singular possessive form is grotto's.
The singular possessive form is lesson's.
The possessive form is Amos's.
The singular form is goose; the singular possessive form is goose's.The plural form is geese; the plural possessive form is geese's.
Quantum is singular, not singular possessive. The singular possessive form is quantum's.
The singular possessive form is speculum's.
The singular possessive form is frontiersman's.
The singular possessive form is aircraft's.
The singular possessive form is week's.
The singular possessive form is contralto's.
The singular possessive form is herd's.
The singular possessive form is heart's; the plural possessive form is hearts'.
The singular form for the noun families is family. The singular possessive form is family's.
The singular possessive form of wolves is wolf's.