梁龙属（学名：Diplodocus）是蜥脚下目梁龙科下的一属恐龙，牠的第一副化石是由塞缪尔·温德尔·威利斯顿（Samuel Wendell Williston）所发现。牠的属名是由奥塞内尔·查利斯·马什（Othniel Charles Marsh）于1877年所命名，是从古希腊文的「διπλόος」（意即「一双」）及「δοκός」（意即「横梁」）衍生的新拉丁语而来。这是因牠在尾巴下侧有双叉形的人字骨。这些骨头最初被认为是梁龙独有的特征，但是之后在其他梁龙科及非梁龙科（如马门溪龙）恐龙也有发现这个特征。

Diplodocus (/dɪˈplɒdəkəs/, /daɪˈplɒdəkəs/, or /ˌdɪploʊˈdoʊkəs/) is an extinct genus of diplodocid sauropod dinosaurs whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a neo-Latin term derived from Greek διπλός (diplos) "double" and δοκός (dokos) "beam", in reference to its double-beamed chevron bones located in the underside of the tail. Chevron bones of this particular form were initially believed to be unique to Diplodocus; however, since then they have been discovered in other members of the diplodocid family as well as in nondiplodocid sauropods, such as Mamenchisaurus. It is now common scientific opinion that Seismosaurus hallorum is a species of Diplodocus.