In English? A few verbs do not have an 's' added to the end in the third person singular: 'can', 'may', 'shall', 'must', and 'will are what I thought of (maybe more, I don't know off the top of my head). These are all used as auxiliary verbs in most cases I can thing of.
In Latin? Most third person singular endings are 't' in the active voice, 'tur' in the passive voice if I am not mistaken.