Answer:
The other
Step-by-step explanation:
The Other (capitalized) is the concept that opposes to the "I", it refers to the concept of something/someone outside of oneself.
Sartre particularly talked about the concept of "the Others" mentioning that when someone else emerges into one's picture it is referred as "The Other". Sartre even said that "hell is other people" because he had the idea that there is no way that we are alone in this world and we are always influenced by other people's expectations and opinions, we are seen by other people as a mere object and therefore making the other people "hell to us".
Therefore, the Other is someone or something outside of oneself.