A Takaran wildebeest was a large herding animal, native to the planet Takara.
In 2372, Odo took the form of a Takaran wildebeest as he practiced his shape-shifting.
Quark, whose quarters were directly below Odo's, complained about all of the tromping around Odo was doing, as it was keeping Quark awake. Following the complaint, Odo took the form of a Rafalian mouse. (DS9: "Crossfire")