Yakko Warner is the oldest of the Warner siblings, He is one of the three main protagonists of Animaniacs. (alongside Wakko and Dot).
Out of the three siblings, Yakko easily takes the role as the leader and instigator of many of their escapades, as well as a parental figure for Wakko and Dot due to being the oldest.
The Warner siblings' species is never specified, much to the confusion of the other characters. When asked what they are, the Warners will never give a clear response, with their main answer simply being that they are the Warner brothers and the Warner sister; some other responses include cute and "infested with fleas.