D'Onni was a male Orion who lived during the late 24th century. During the early 2380s, D'Onni worked out of the Orion Pirate Outpost where he created art forgeries. D'Onni was a cousin of Starfleet ensign D'Vana Tendi.
In 2381, Tendi and Beckett Mariner diverted to the outpost with the hope that D'Onni could repair a broken Caitian libido post. D'Onni was initially worried about being seen talking to Tendi, but after she asserted herself he kissed her boots and said he would do anything for her, addressing her as "Mistress of the Winter Constellations".
Because Mariner was Human, she was disguised in false green to appear Orion. When Mariner's skin color reverted to its natural color, she and Tendi were forced to flee, leaving D'Onni behind. (LD: "We'll Always Have Tom Paris")
Later that year, D'Onni attended his other cousin D'Erika Tendi's wedding on Orion. (LD: "Something Borrowed, Something Green")
D'Onni was voiced by Tom Kenny in "We'll Always Have Tom Paris".
He was given the full name "D'Onni Tendi" by StarTrek.com.