I may have made some mistakes when answering DQs - in the interests of clarity I will expand those answers which may be ambiguous.
My initial is L and…
1: I am real
2: I am male
3: L is the initial of my last name
4: I am not American.
5: I am not living.
6: I am not known for the arts
7: I died since 1900
8: I am European
9: I am not British
10: I am not a political or military figure
11: I died before 1975
12: I am not French
13: I am known for the sciences
14: I was born before 1900
15: I am not a sports figure
16: I am not a native speaker of a Slavic language
17: I died after 1950
18: I am not from a former Warsaw Pact nation
19: I am not a native speaker of a Germanic language. I was born in a country in which the majority language is Germanic, but in a region of that country where the majority language is not Germanic. I published my best known work in a non-Germanic language
20: I was born west of Vienna
21: My best known scientific achievement was before 1930. My best known scientific achievement is related to an idea I first articulated before 1930, and developed at length in a book I published after 1939
That’s us past 20. Anyone who has a DQ is now entitled to ask “Are you [name]?” As guylvesque didn’t have the benefit of these clarifications when he made his guess, I’ll let him have another.
IQ1: Did you work at Blair General?
IQ2: Was the wreck of one of your ships found in the Dominican Republic a few years ago?
IQ3: Did you play a missionary in Africa, a queen of England, and an antique-shop owner?
Other than Leonard Nimoy, are you an actor who narrates many PBS science and nature shows? - Liev Schreiber
Were you a famous scientist about whom a humorous song was written? - Yes, Lobachevsky
Were you the person who composed and sang that song? - Yes, Tom Lehrer
IQs:
Are you an actor who worked in the White House as a staffer?
Did a critic comment on your ill-fitting uniform?
Did you say you’d gladly accept a demotion if it meant more lines in the script?
1: As you say, you are not Kublai Khan
2: Then you are not Kryten from Red Dwarf.
3: Then you are not Kiera Knightley, who played Georgiana, Duchess of Devonshire in The Duchess and Governor Swan’s daughter, Elizabeth, in The Pirates of the Carribean*
DQ1: Is K the initial letter of your last name?
DQ2: Are you currently alive (or, if fictional are the setting and your storyline such that you would be currently alive?)
IQ1: Did you direct a film wich included Also Sprach Zarathustra in its soundtrack?
IQ2: Were you an English actor who starred in a film based on Mary Shelley’s book?
IQ3: Did you drive your car off a bridge near Martha’s Vineyard?
IQ1: Did you take a name beginning with K when you were ennobled?
IQ2: Did you appear in both Star Trek and Babylon 5?
IQ3: Did you make McDonald’s what it is today?
1: I was thinking of William Thompson, Lord Kelvin, but I’ll accept Ghengis Khan as an answer.
2: Walter Koenig played Chekov in Star Trek and Bester the Psi-cop in Babylon 5
3: As you said, Ray Kroc.