Masculine Feminine Neuter
aliquis aliquis aliquid someone, something
quisquam quisquam quicquam anyone, anything
quisque quisque quidque each one, each thing
quidam quaedam quiddam a certain person, a certain thing
quivis quaevis quidvis anyone whatever, anything whatever

Qui and aliqui are sometimes used instead of quis and aliquis (nom. sg. m.)
The nominative and accusative plural of quid can be either quae or qua.
The nominative and accusative plural of aliquid is almost always aliqua.
The accusative singular of quidam is quendam.
The accusative singular of quaedam is quandam.


Masculine Feminine Neuter
aliqui aliqua aliquod some
quisquam quisquam quicquam any
quisque quaeque quodque each
quidam quaedam quoddam a certain
quivis quaevis quodvis any whatever

quis and aliquis are sometimes used instead of qui and aliqui (nom. sg. m.)
Quisquam has no plural forms.

Quis is most often used with si [if], nisi [unless], ne [that not] and num [surely not?].
In other cases, aliquis is preferred.
si quid his accidat. [If anything should happen to them.]
aliquid his accidat. [Something may happen to them.]