I do not think of any one person. Some people do. They think of someone they know or a historical figure. Maybe they think of someone they read a book about or a character in a movie. I think according to my training. I have training in cognitive and behavioral therapy. I have extensive reading in development and attachment. I have read information on life narratives and meta-narratives. I have read and really appreciate psychodynamic theory and psychoanalytic theory. I like object relations a lot. I say all that to say that mental illness or mental health have gone through a change in definitional concepts. We no longer spear of people being out of touch with reality as the sole indicator of a problem with people being falling closer to reality and farther from reality. Instead, we speak of dysfunction. We moved from the idea that a person's cognitions showed illness if they were farther from reality and so, in all training, therapists were expected to have excellent abstract and symbolic reasoning. In order to gain entrance into many therapy programs one used to be required to take the Miller Analogies Test (MAT). In addition, a great deal of logic was taught. It was felt that most people who came into to see a therapist were not so bad off that they could not be reasoned with. A lot of people were seen as having more of a moderate to slight emotional disturbance and so most therapists were assumed to see that alone. That was not a bad assumption. Today, however, with the medical field believing that a perfect one-to-one correspondence exists for chemistry to mental function, we have moved away from analyzing symptomology apart from chemistry. Now, this is very good in some ways, but it cannot be based on a perfect or imperfect correspondence between neural chemistry and mental state. In fact, the actual studies show and prove over and over again that mental state is not in any correspondence to neural biochemistry. Reverse diagnosis with medication is a cause for malpractice and a lot of implied diagnosis is based on broad studies of chemistry and the specific medication effects. We know that the medication has a broad effect and will cause calming in most instances. The medications given can increase certain neural chemical concentrations or reduce them, but that is a far cry from establishing that the neural chemical is causing the emotional problem. Most people do not want to think this through and they want a way of calming themselves or dealing with depression or bipolar, etc., so they willingly take a pill. Pills do not take care of problems of meaning and almost all problems of life are attached to a person's list of significant meanings for them. Everyone has a list like that and there is evidence from empirically informed studies to demonstrate that such a list is operational. It has cognitive structure or pattern or is established as a grid. Once that grid develops its key characteristics it is used to validate the identity. That functional aspect makes the cognitive grid more difficult to address because, by strengthening the identity, it stabilizes the psychological or emotional energy that the person is working with. In a practical way, the psychological or emotional energy a person is working with forms an economy inside of them. It has to be shared internally between the Id, the Ego, and the Superego. They way that it does this causes or relieves problems of intensity. If you think of the Id, the Ego and the Superego as banks that loan energy to each other based on trust, you can see the problem if a person has experienced manipulation in their early years (as this will impact attachment and a sense of self and others), abuse or neglect. When abuse, manipulation or neglect occurs early and is characteristic of the attachment relationships, the economy of psychological energy or emotional energy is not developed well and what usually happens is that the Id (from which all the psychological energy comes from) withholds the psychological energy from the Ego and the Superego. This makes the Ego seek for support external to itself and leads to the behaviors that are identified colloquially as "very needy." It can lead to a form of hyper-dependency and personality disorders that display that. It can make the Superego initially very demanding and then compromised so that ethical concerns and moral concerns and not understood other than for their discussion or manipulative aspects (leading to a form of socio-pathology or psychopathology). These states are justified by life narratives with primarily unhealthy life narratives being dominant. Those life narratives to start with are: 1) "I'm inadequate;" 2) "I'm insignificant;" 3) I'm incompetent;" and 4) "I'm invalid." Those are not the only ones but they are primary. They lead to a need to find ways to manage the psychological energy and most of these replicate the abuse/neglect/and / or manipulation. People can self-neglect as a pattern and they will find people who will take advantage of them. People can learn only to manipulate as a normal way of having intimacy and they will seek persons out that are manipulatable. The cognitive aspects need to be altered. That is the actual thoughts need to be worked through and changed, but often under-trained therapists will try to merely change the thoughts or the behaviors without tying them to the economy of emotional energy internal to their client and this will cause the client to slow down and even stop working their therapy. The under-trained therapist will then state to themselves (and they are often encouraged draw this type of conclusion by their supervisors who are also undertrained), that the client is just resistant or "just not ready to change." When we look at a Hitler and we see the list of significant personal meanings he has (we can see this in his book and other writings), we can see how he is attempting to attach to the world as a whole (a form of pathology) through manipulation and abuse---as though these are ways that he finds a form of intimacy for his own Id. Now most people move past this very early in life. They move to finding almost all of their intimacy through their Ego which is informed by their Superego. The Ego is the stress balancing and integrative mechanism for all experience. The Superego informs the person out the outer limits of conclusions by developing ethical systems and moral propositions. We see that power-wonks in general---those people who seek power for money or primarily for prestige that they have in no other area of life---have an under-developed Superego process. Symptomology is not the way to determine what they are suffering from, although the present APA has opted for that form. They will eventually change it to cause. You have a wonderful day.

I suggest you start here at the link I pasted below. It will take you to the DSM5. This is the authoritative source on all things related to your question.
Like most people with a functioning brain I believe the DSM is flawed. Most of those perceived flaws I believe are the result of a paradigm shift in the mores and general understanding of "right vs "wrong" in Western societies.
This paradigm shift is reflective the radically increased level of secularist ideologies that guide or otherwise influence behaviors of citizens in general.
The spectrum of that which is "normal" vs that which is "abnomral" is much wider than it was in say the DSM 3 and 2 before that and of course the original iteration of this manual.

[psychiatry.org]

As a layman and an armchair observer of human beings who is at best caually acquainted with the DSM that all mental disorders and illnesses are pathological but not all pathologies are classified as mental disorders or illnesses.

There are a LOT more people walking around today (and driving cars and owning firearms and working in potentially dangerous (to others) jobs who are taking one kind of psychotropic or another. And all have been "diagnosed" with some kind of pathology or illness in order to validate the prescriptions put out by their psychiatrists.

My first was was diagnosed as having "Borderline personality disorder" - let me tell you it is impossibly difficult to deal with someone like that in the workplace or in the neighborhood but to be married to someone who has BPD will just about cause you to go to great extremes yourself in trying to cope with it.

I'm not a big fan of stretching pathologizing normal people. That's VERY popular right now. So, compromised clinicians have argued literal DSM-v diagnoses for Trump. The same SHOULD be said of a number of leftist senators, including Pelosi, Schumer, Schiff, Nadler, Blumenthal, Hirono, on and on and on--Hillary easily. If Trump's literally mentally ill, then those and more are too.

But, none of those ppl are really mentally I'll, and it's damaging to mental healthcare to distort MH by politicizing it. Dangerous and short-sighted.

Mental illness is serious. Every anxious person is not mentally ill. 'Toxicity' is not mental illness (or even a real thing outside of its political purpose). Depression TO ME is a mental illness only in the absence of all agency. There is a complete collapse of coping strategies, negative and positive. PTSD has actual criteria, and those criteria are too often ignored these days. It's like anyone who's ever felt bad has PTSD. Therapists are stretching the definitions of actual disorders.

So, really, severity is important.