It's very rare that a fighter just has one fight in the UFC, once that fighter has made it there.
The usual standard for a fighter losing their debut, is that they get at least one more fight to redeem themselves. If they don't, they are usually released after going 0 - 2.
Here though, are some one and done UFC fighters. Not counting any fighters one and done before 2001 (Zuffa purchase) - so no Kazushi Sakuraba when he fought at UFC Ultimate Japan in 1997 (...twice in fact due to a referee error - the early days were a lot different).
Maiquel Falcao
1 - 0 in the UFC. Defeated Gerald Harris at UFC 123.
Neil Wain
0 - 1 in the UFC. Lost to Shane Carwin at UFC 89.
James Zikic
0 - 1 in the UFC. Lost to Phillip Miller at UFC 38.
Neil Grove
0 - 1 in the UFC. Lost to Mike Ciesnolevicz at UFC 95.
Dmitriy Sosnovskiy
1 - 0 in the UFC. Defeated Mark Godbeer at UFC FN 127.
Jimmy Flick
1 - 0 in the UFC. Defeated Cody Durden at UFC FN 183.
James Tony
0 - 1 in the UFC. Lost to Randy Couture at UFC 118.
Am I missing any?