What makes a Actor great?
Years of training and experience, huge natural talent, versatility and the ability to say your lines with total sincerity and like they've never been rehearsed or said before. Also being able to follow direction, intelligence, a great work ethic, a great imagination and one thing that cannot be taught - the ability to appear completely credible and convincing.
Talent, training, perseverance, intelligence and a well developed sense of humor and empathy. All of those things allow them to focus on how to understand and develop a character, deal with the rejection that is part of the process, the ability to convincing portray a character, and work well with others. It isn't an easy, one size fits all life path but it can be very rewarding for the right person even if they never become rich or famous.
they care about the project and give 100% of their heart and soul
good training and skills,lots of empathy, practice and reflection
The ability to convey an intended emotion or quality. For example the bear attack scene in the movie Revenant, Heath Ledger's role as the Joker or Christian Bale's role in the movie Machinist. Denzel Washington in Man on Fire and Will Smith in Pursuit of Happiness. All of these characters the actors portrayed fictional or not I was able to relate with and feel what they were feeling.
Sometimes a great director.
Mostly depends on him, how passionate he is, how importance he keeps in his career and son on.
talent and looks