Hazel Bertha Hill (21 July 1920 – 28 September 2010) was a British Child Psychiatrist, probably best known for her contribution in changing an Air Ministry specification of firepower to be carried by new fighter aircraft before the Second World War.

In June and July 1934 they worked at night to create the evidence that her father's boss needed to justify making a large change in the design.

They calculated that 256 bullets in two seconds would be necessary to bring down an enemy bomber at the increased speeds of the new aircraft, and for this eight guns were required.

[3] Hazel's son, Robin, said he thinks his mother enjoyed maths because she was partially dyslexic and had trouble with spelling.

After school, Hill studied medicine at a university in London and joined the Royal Army Medical Corps after graduating in 1943.