Unfortunately I don't cope well with heat and we've been going through heat wave weather here in the UK for weeks on end now. Consequently I've been rather unwell and not spent a great deal of time computerin'.
I don't like heat either.
Fortunately I have air conditioning to escape to.
And my re-play of Blade Runner has ground to a horrible halt
What happened? Stuckness or technical problems?
Anyway, I'm sure there are plenty of folk who will have different heroes to Gabriel Knight - so maybe they'll pop in and mention them ??
I'm not sure about "heroes" but here are some player characters I enjoyed:
Sylvie Leroux (Chronicles of Mystery)
Constable Zellner (The Raven)
Gus McPherson (Post Mortem and Still Life)
As-Sayf/Tancred de Nérac (Legend of the Prophet/Secrets of Alamut)
Nefermaat/Tifet (Egypt 2: The Heliopolis Prophecy)
Maya (Egypt 3: The Egyptian Prophecy)
the unnamed creature in Oknytt
Mina (Return to Mysterious Island)
Bobbin Threadbare (Loom)
Bradwen (Arthur's Knights 1 and 2)
Watson (Sherlock Testament)
Poirot (Agatha Christie Evil Under the Sun)
Nancy Drew (Lani Minella)
Lara Croft (1996 version, not current version)
April Ryan (in The Longest Journey, not the Dreamfall games)
King Graham (KQ 1,2,5)
and of course Gabriel Knight has already been mentioned.
I don't know if Sherlock or Poirot would have been as memorable without having read the books, or Indiana Jones as memorable without the movies.
Then there are some memorable characters you don't play as, such as Mephisto in Faust, Atrus in the Myst series, Catherine in Riven, Saavedro in Myst III, Wolfgang Ritter in GK1, etc.