Piled Higher and Deeper introduced its main characters early in its run, and their personalities have remained fairly constant during the strip's several years of publication. In the strip's first few seasons, the characters were clearly
Stanford University students, though the number of school-specific references and jokes has decreased since. Cham has said that while the characters are not based on real people, he was inspired by colleagues, classmates, and his brother's friends. Cham chose to make the character nameless as "when you're a graduate student, professors never remember your name." As he is seen playing with two children at home during his winter vacation, he probably has younger siblings, nieces and/or nephews, or cousins. He has been increasingly seen with a set group of friends (one is named
Mikkel) and seems, at least marginally, to be the most favored graduate student of his advisor, Prof. Smith. At the conclusion of the film, the character states for the first time that his name is
Winston, named after Jorge's father; in the films, Winston is a
biochemistry grad student. •
Cecilia – A geeky engineering student though earlier strips have her born in 1973. Cecilia spent years refusing to admit that she was truly a
geek at heart. However, in one strip she finally with hesitation admitted she is indeed a geek. She is also a programmer as well. Addicted to chocolate and cookies, she has long since taken enough classes and conducted enough research to graduate, but a mysterious psychological force keeps her in school. She stated in an interview for a project by her friend Tajel that her father was a professor, a "great teacher", something that may or may not be a motivation for her to go above and beyond (also, her choice of words indicates that her father may have died). During class, she deliberately wears frumpy clothes to discourage male interest, since the vast majority of her classmates are men. This strategy is not always successful – "Excuse me, female, will you marry me?" She has had two boyfriends in the course of the strip: David and Scott. Although she broke up with David relatively quickly, she seriously dated
Scott, her crush in high school, for numerous strips; they had a
long-distance relationship for a while after Scott was promoted and moved to London but broke up amicably in 2007. Cecilia sometimes accompanies Tajel to political rallies and such events. She was asked in 2006 by a professor to interview for a faculty position at a different institution because "it's the only position you're not overqualified for" and "we hired one of their grad students, so, diplomatically, they owe us." •
Michael Slackenerny – phenomenally lazy, yet had been in graduate school for longer than anyone can remember (during one of his interviews it was strongly implied that he started grad school in the 1980s), surviving on
ramen and free food from various events on campus. He views grad school not as a place but as "a state of mind [...] preferably sleeping". In the spring of 1998, he drove to
Las Vegas with a seemingly foolproof plan to beat the
blackjack tables, thereby winning enough money to solve Stanford's housing crisis. Instead, he returned with a wife,
Jen, who remained an
unseen character for some time. Jen became pregnant with their daughter
Sophy and stayed that way for several years, constantly urging Michael to finish his thesis and graduate. Michael finally completed his doctoral defense in 2005 – Jen went into labor just before his presentation began – but did not finish writing his thesis until 2007. After submitting his dissertation, Mike was seen walking home and asking himself, "Now what?" After a period of job-hunting, he was finally hired by Prof. Smith as a
postdoc. •
Tajel – an
anthropologist and the lone social scientist in the main cast. She was Cecilia's roommate before getting married. She is a dedicated
activist who frequently attends or organizes rallies. Her frustration with American politics is exacerbated by her not being a United States citizen. She is conversant in Spanish. Her mother is Indian and her father is Caucasian. She married Dr. Khumalo in February 2009. •
Gerard – the strip's newest "official" character, he is a major in Medieval
Scandinavian Cultural Philosophy, who was personally introduced to readers by Tajel, supposedly in response to numerous letters from Humanities majors requesting their own character, and was meant to provide jokes on "obscure manuscripts, dead languages, and being the lowest paid grads on campus. Also,
political correctness!" Despite this, Gerard has only been shown twice after his initial introduction, apart from a cameo as a guest at Tajel's wedding, in a joke on the obscurity and uselessness of his field. His first actual storyline within the comic occurs when he is informed that funding has been cut for humanities majors and to leave the strip or find a more useful major, subsequently forcing him to justify why the comic should retain a humanities character. •
Dee – the hero's younger sister. She is an
undergraduate student who has been seen taking the
GRE. She also talks on her
cellular telephone, eats quite a bit, and naps during class when she is not doing something even more inappropriate, such as chatting or eating a full meal during a test. Dee once phones her "sister dearest", so the main character may have more than one sibling. Dee has a good male friend who she often spends time with and at one point hints that he may have romantic feelings for her. Like the main character, he has not yet been named. •
Mariko – a
Japanese student in the same research field as the hero, she visits Prof. Smith's lab in 1998. Smith assigns her to work with "whoever is lowest in the lab hierarchy", which turns out to be the hero. During her brief stay, she inspires in him a powerful
unrequited affection, which he maintains for at least three years. She eventually quits her
Ph.D. and starts her own company, at which the hero works briefly. She is still occasionally seen talking with the main character as he works, so her current status is somewhat murky. On a strip dated 28 April 2010, entitled "Lost no more..?", she was seen in an alternate timeline as possibly being the mother of the Nameless Hero's (supposed) baby, with the Nameless Hero asking "WHAT IF I HAD STAYED IN ACADEMIA?" •
Steve (
aka. Golden Boy) – Remarkably clever, sincere and "good boy". Steve has been in graduate school for two years and has already completed his thesis. In the lab hierarchy he is given more consideration than any of the post docs or research associates by Prof. Smith. He is extremely good in getting positive results and is always consulted by Prof. Smith for his opinion. His "good boy" image in comparison to the nameless hero is a running joke in the series. •
Allison – The sole female PhD student in Professor Smith's lab, which Smith and the other PhDs often forget to Allison's frustration. Unlike her labmates, she is not distracted by sporting events like the World Cup and proves to have some measure of athletic ability during the students vs. professors baseball match.
Faculty •
Professor Jones – Cecilia's research advisor; a typical graduate school professor, although seemingly older and kinder than Prof. Smith. He is clueless in giving Cecilia advice on non-research related topics such as her love life and future career, and will ask for her help with small tasks such as changing the font size of footnotes, claiming it is urgent. Apparently the only reason he has time to see his wife is because he married his administrative assistant; before he received tenure, he had already been divorced three times. He has a daughter in 1st grade named Shelley, who is intelligent enough to fix Mike's work for him. •
Dr. Patrick Khumalo – An adjunct professor in the Anthropology Department's faculty, whom Tajel eventually marries. •
Professor Rivera – Tajel's advisor. He apparently takes a laid-back approach to being an advisor, being entirely clueless as to Tajel's research interests, progress, and sometimes even her name. Once he praised a draft of a paper that Tajel had written, three months after Tajel had already submitted the final paper on due date. Additionally, he is extremely elusive when needed, such as when Cecilia needed to find him for documents to allow Tajel to renew her visa, appearing only when Cecilia tried imagining he was the last person she wanted to see. He is married to Professor Stein, the chair of the anthropology department. Despite being aware that he lacks any apparent interest in Tajel's work, she is still stunned when he leaves for a position at another university with only an offer of advising her remotely. •
Professor Galvez – The head of the anthropology department, who becomes Tajel's new advisor after discussion with the rest of the faculty. In contrast to Rivera, Galvez apparently has a surly personality and finds Tajel's emails to be too lengthy to bother reading. •
Professor Brian S. Smith – Mostly intimidating and unsympathetic but sometimes forgetful, Prof. Smith advises Mike Slackenerny and the Nameless Hero in their research, taking credit for any output his lab actually produces. Prof. Smith occasionally tries to "fit in" with his students (nearly all males and one female student, Allison ), to humorous and awkward results. He has a wife and two children, a daughter named Sadie, and a son, "Junior". However, as a grad student, Prof. Smith (then known simply as "Brian") fell in love with a fellow grad student in the same lab, Sangeeta Singh, whose work he greatly admired. Tragically, Brian ignored Sangeeta's advances in order to work overtime on his thesis, even turning down her invitation to a holiday party. Prof. Smith regretted it for the rest of his life, consoling himself many years later by saying to himself, "who cares, I've got tenure". The second PhD Movie elaborates on this further, showing Sangeeta's fate after young Brian stupidly missed the opportunity of a lifetime with her: decades later, Sangeeta is a professor herself and one of Prof. Smith's leading rivals in his field. But even then, it is clear that Prof. Smith never got over her. When she encounters him at a scientific conference, taunting his work, he has no wits to reply and can only stare longingly at her, until she finally snaps him out of his trance. It is unclear whether she still harbors a buried affection for him in return. Prof. Smith's current wife presumably hopes not. Prof. Smith was originally drawn so that his face was never seen, much like
Ernst Stavro Blofeld in the early
James Bond movies,
Doctor Claw in
Inspector Gadget, or any teacher/adult in
Peanuts. According to his wife, Smith apparently "used to goof off all the time as a grad student" and it has been suggested on occasion that he had been interested in becoming a circus performer rather than a professor. A brilliant academic who disproved all the theories of his advisor Professor Emeritus Zekowsky, Professor Smith is the Arthur C. and Caroline J. McCallister Distinguished Chair Professor and Anderson Faculty Scholar, and the Director of the Center for Computational Research and the National Institute of Dynamical Physics. He is the recipient of the
Alexander von Humboldt Prize of the Netherlands, the
National Science Foundation Presidential Investigator Award, the Exceptional Achievement Medal from the International Society of Engineers, the Pi Gamma Tau Industry Excellence Professorship, the National Medal of Engineering, and the
Medal of Honor from the Royal Academy of Scientists. He serves on the editorial board of the
Journal of Advanced Dynamics, the
Journal of Nano-Particle Computation,
Physik-Publication and several other journals, and on the advisory boards of many industry
consortia. He holds honorary doctorates from the
Universidad Politécnica de Madrid, Tsing-Chua Beijing University and the
University of São Paulo, among others. •
Professor Sangeeta Singh – Prof. Smith's ex-labmate when he was a grad student himself, and now his greatest rival, Prof. Singh is featured solely in "The PHD Movie 2", although she was seen in Prof. Smith's flashbacks during the "
A Smithmas Carol" storyline. ==Parodies==