Eucalyptus aggregata, commonly known as black gum,[3] is a medium-sized tree that is endemic to southeastern Australia.

It is a component of grassy woodland, often in low-lying or swampy areas, much of which has been cleared and it is under threat.Eucalyptus aggregata grows as a medium-sized tree, reaching 18 m (60 ft) in height, with dark grey to black rough bark that is fibrous and flaky on the trunk and smooth whitish, cream-coloured or greyish bark on the uppermost branches.

[3][4][5][6][7] Eucalyptus aggregata was first formally described by Henry Deane and Joseph Maiden in 1900 from material collected at Wallerawang as the lectotype.

Eucalyptus aggregata grows in woodland and is associated with candlebark (Eucalyptus rubida), ribbon gum (E. viminalis), black sally (E. stellulata) broad-leaved peppermint (E. dives) and snow gum (E. pauciflora), with a grassy understory of river tussock (Poa labillardieri) and silver top wallaby grass (Joycea pallida).

The soil is generally poorly drained, alluvial or swampy, with the black gum growing in low-lying areas.