Ego

Ego was a person's sense of self-esteem or self-importance.

Astonished at the sight of the Fifth Doctor regenerating, Peri Brown stuttered and said "three Is in one breath", to which the newly regenerated Sixth Doctor remarked made her sound like a "rather egotistical young lady." (TV: The Caves of Androzani)

While Peri was underwhelmed when the Doctor's TARDIS securely landed in the solar system in 1985, the Sixth Doctor commented that "a little gratitude wouldn't irretrievably damage my ego." (TV: Attack of the Cybermen)

Jobel voiced his belief that it would take a mountain to crush the Sixth Doctor's ego. (TV: Revelation of the Daleks)

The Twelfth Doctor stated that Errol Flynn "had the most enormous ego." (TV: Robot of Sherwood)

After her eleventh regeneration, the General rhetorically asked how men continually dealt with "all that ego", having been a man in her previous incarnation. (TV: Hell Bent)