Example: Algebraic Multiplicity vs Geometric Multiplicity Is there a simple example of a matrix having an eigenvalue whose geometric multiplicity is strictly smaller than its algebraic multiplicity?

Consider $$ A = \begin{pmatrix} 0 & 1 \\\ 0 & 0 \end{pmatrix} $$ As $\chi_A(t) = t^2$, $0$ has algebraic multiplicity $2$, but geometric multiplicity $1$.