The Scorpio ascendant squares Pluto in exaltation in Leo in the ninth house of profession. Scorpio is associated with compulsiveness while Pluto (god of death) is associated with intensity and the inner psyche. Pluto is the modern ruler of Scorpio as well as being Williams’ overall chart ruler. His Sun (eccentricity) is in Cancer (moodiness) in the ninth house.
Pluto is conjunct Mercury (planet of the conscious mind). Mercury is in its Fall in Leo. Leo is associated with the dramatic and need for recognition. His Scorpio ascendant is indicative of the mask/persona he portrays to the public. The public is represented by the MC on the cusp of the tenth house of career in his natal chart.
The hemispheric planetary distribution indicates an excessive extroversion. His chart's ominous aspect between his ascendant in Scorpio and Pluto in Leo is further amplified by his chart's sign signature. His sign signature is cardinal as to quality (with mutable second) and water as to element, indicating he is energetic, driven and unstable.
Uranus (sudden upheavals) is conjunct Mars (destruction). Mars is in Fall in Cancer. Cancer is the natural sign of the fourth house of home. Cancer is associated with moodiness in the eighth house of death. Cancer is ruled by the Moon (subconscious mind).
The Uranus-Mars conjunction square Neptune (self-delusion) in Libra (discontendedness) in the eleventh house of aspirations.
Williams’ natal Moon in Pisces (mutable water) is associated with the subconscious mind and the fourth house of home forms a trine aspect with the ascendant . Generally a trine aspect is favorable but because his ascendant is in Scorpio his natal Moon in the fourth house is greatly afflicted due to Via Combusta! (For more information on Via Combusta, click here.)
His natal Moon's affliction is further reinforced by being part of a Grand Water Trine with the first house ascendant as well as the eighth house Stellium of Uranus (extremes), Mars (injury), and Lilith (denying/malefic). His natal Moon is also in an aspect of opposition with Venus (disharmony since Venus is in Fall) in Virgo in the tenth house of career. His South Node in the tenth house in Virgo accents the tension with his North Node in the fourth house in Pisces in the most private (personal) part of the chart.
Robin William' s natal chart manifests a rare configuration termed "Lucifer's Rectangle" (Asc trines Moon / Desc trines Venus). This configuration manifests in the chart of the founding date for the Church of Satan, the natal chart of Allister Crowley and Friedrich Nietzsche. (Click here to read more on the Lucifer's Rectangle.)
Lilith in the eighth house of death is in opposition to Chiron in the second house of self-esteem. Saturn (loss) squares Chiron as well as Lilith forming a T-square configuration. The T-square is composed of hard aspects thus offering difficult challenges to the native.
In Robin William's chart this T-square draws attention to the house where the missing fourth leg would be -- indicating the area of life where he will meet his greatest challenge, namely, the fourth house of home.
 AA Chart data from Astrodatabank. https://www.astro.com/astro-databank/Williams,_Robin