  We consider the translational hull $\Omega(I)$ of an arbitrary subsemigroup
$I$ of an endomorphism monoid $\mathrm{End}(A)$ where $A$ is a universal
algebra. We give conditions for every bi-translation of $I$ to be realised by
transformations, or by endomorphisms, of $A$. We demonstrate that certain of
these conditions are also sufficient to provide natural isomorphisms between
the translational hull of $I$ and the idealiser of $I$ within
$\mathrm{End}(A)$, which in the case where $I$ is an ideal is simply
$\mathrm{End}(A)$. We describe the connection between these conditions and work
of Petrich and Gluskin in the context of densely embedded ideals. Where the
conditions fail, we develop a methodology to extract information concerning
$\Omega(I)$ from the translational hull $\Omega(I/{\approx})$ of a quotient
$I/{\approx}$ of $I$. We illustrate these concepts in detail in the cases where
$A$ is: a free algebra; an independence algebra; a finite symmetric group.
