Thanks mondrian for your fast response about this man's portrait, that seems to be rather legible, for your question was asked around here and most people's first choice was Dr Sigmund Freud too!
Tintin's character # 1
is most likely the 'unseen' cameo of Freud
(1856-1939), the father of psychoanalysis*, for this man's sketch by Herge in 1929 does actually match with:
no known picture of Alfred Zwaenepoel.
the spontaneous designation of Freud by people who don't know about Tintinoliterature, but are still educated!
Freud's deformed right jaw, the result of the many facial operations undergone since 1923 for a cancer.
the many puns* & slips of the tongue read in the corpus, that call up those described by Freud in Psychopathology* of Everyday Life
see The Castafiore Emerald* & Les Bijoux Ravis*
Tintin being kind of a psychoanalysis* for Herge, as he went on drawing Tintin but left a likely depressing Jungian
psychoanalyst (Dr Ricklin*, Zurich, Switzerland, 1959) who firmly recommended he should stop with Tintin, as reported in Herge
by P.Assouline, 1996, chapter 10.
see also http://www.youngvic.org/imgs/resourcepack/11343963
the early and narrow links between Tintin and psychoanalysis*, links confessed by Herge himself and clearly reported by N.Sadoul in the film Tintin et Moi
a known figure good at displaying words about people's imaginary thoughts, but unable to read 'images'**, for Freud refused to admit what his eyes could see in 1886, when they saw patently abused children.
Eleven years later, he published a most personal theory based on a much distorted Oedipus' myth
that wouldn't point at his own childhood and own father's misbehaviour,
but would try and solve his personal problem by infering children were responsible for being abused!
He reportedly didn't apply his own theory during his whole lifetime, but alas "Freud's courage in acknowledging the extent of [child abuse] was not shared by the majority of his colleagues. Most, like Jung, simply avoided the topic. Others, who noted that large numbers of their patients had clear memories of [child abuse], blamed the victim, saying (...) that the molestation "was desired by the child unconsciously (...)"
full text on http://www.psychohistory.com/index.html
in article about 'Universality etc', 14th paragraph.
This smart theory is still echoed in 2006 by scholars who most seriously ban 'abuseur' (abuser) from their vocabulary!
Fortunately other scholars publish more empathic & more relevant studies on the subject, such as the recent 'Livre Noir de la Psychanalyse' (by C.Meyer, Les Arenes, 2005) that recalls, in its very subtitle 'How to live, think and feel better without Freud'
that psychoanalysis* can also harm patients.
Some may even find better relief just by themselves, e.g. by the means of writing & doing ...art!
* please search for related threads.
** such an aniconete
* 1st character matches rather well with an 'unseen rebus'*.
*** "Vivre, penser et aller mieux sans Freud".