Definition
The theta role of an agent is typically regarded as the initiator or doer of an action. Agents frequently occupy the subject position, but they may appear in other positions. (Carnie, 2006, p. 229)
All Sḵwx̱wú7mesh roots are inherently intransitive and consequently may only co-occur with one argument, which is realized as the subject. Thematically, this argument may be either an agent or a patient. (Jacobs, 2011, p. 48)
In Halkomelem, many roots such as ʔéxʷeʔ— ‘give food’ are active or agent-oriented. (Suttles, 2004, p. 54)
Examples

References
Carnie, A. (2006). Syntax: A generative introduction. John Wiley & Sons.
Suttles, W. (2004). Musqueum reference grammar. UBC Press. SFU Student Access.*