Beth omega is a singular strong limit above the continuum ($\mathrm{cf}({\beth }_{\omega })=\omega ,2^{\omega }<{\beth }_{\omega }$)

The Beth numbers ${\beth }_0={\aleph }_0$, ${\beth }_{n+1}=2^{{\beth }_n}$ form a strictly increasing countable sequence by Cantor's theorem. Their supremum ${\beth }_{\omega }$ has cofinality $\omega$ because no finite subset is cofinal. It exceeds $2^{{\aleph }_0}={\beth }_1$. It is also a strong limit cardinal: if $\rho <{\beth }_{\omega }$, some $n$ has $\rho <{\beth }_n$, so $2^{\rho }\le {\beth }_{n+1}<{\beth }_{\omega }$. Thus the singular cardinal example needs no Continuum hypothesis.