Oh man, I just got through reading "The Legacy of Unicron" today (for the first time) and I now have new respect for Death's Head.
As I was reading these Marvel UK comics, I kept envisioning the late Tony Jay's voice coming out of Death's Head's mouth.
Here's a few good quotes from him:
(
*When asked where he's going*) "To find Galvatron... To
kill Galvatron."
"Predictable. You Decepticons seem unable to accept the simple fact that you have superiors. Oh, and Scourge... I don't like the term bounty-hunter, right?" (
*shoots him*)
Death's Head: "Name's Death's Head. Rather no one knew I was here, yes? Makes you an endangered species, eh?"
Bumblebee: "Huh! Says you!"
Death's Head: "Yep." (
*destroys Bumblebee*) "Heh - Going to like it here,
yes."
(
*When offered to extract revenge on Rodimus Prime*) "And where's the
profit in that, eh? Revenge may be satisfying on one level, but it doesn't pay the
rent, right? I'm a
businessman, Blot. Make me an offer and we'll talk, yes?"
(
*Whilst ambushing Rodimus Prime*) "I'm disappointed, yes? Hoped you'd be a more
elusive prey. But no. you surround yourself with weak, ineffectual warriors. Dispatched in no time, they were! Then, like some
amateur, you allowed yourself to be
panicked. Left wide open for attack, yes? What happened to the Prime who once bested the mighty Galvatron, eh? No answer, huh? Like I said - Disappointing. Still, a job's a job. I'll make this as swift as -- What?" (
*the floor collapses beneath them*)
"No hard feelings, Prime. For what it's worth...
this is just business, yes?"
(
*To Cyclonus and Scourge*) "Sloppy. Should have
checked, eh? Made
sure. Shield took the blast, yes? Impact just stunned me. You
interfered! Cost me my
kill, yes? Possibly cost me the ten thousand Shanix your leader, Shockwave, placed on Prime's head,
yes? Tried to kill me -
Botched it! Death's Head won't make the same mistake!"
Shockwave: "Ah, Death's Head -- So good to see you again!"
Death's Head: "Stuff the pleasantries, Shockwave -- This
isn't a social call, yes?"
(
*Having killed Shockwave*) "You were a worthy opponent, Shockwave. Under different circumstances I might have even
enjoyed our fight! As it is... this makes me feel
sick! And though you won't be around to see it... rest assured that as soon as I get the chance... I'll avenge
both of us, yes?" (
*crsuhes Shockwave's brain module with his fingertips*)
"
DIE -- No! Will... Will not be used this way!
I... defy... you... UNICRON!" (
*And he does*)
"
Undetected? Hah -- Frightened of Prime, yes? Frightened that the
Creation Matrix he carries within him can destroy you, eh?"
"
I DEFY YOU, UNICRON, YES?" (
*Death's Head shoots at Unicron*)
Unicron: "Mmm --
I'm impressed!"
Death's Head: "
Save it, yes? Eventually, I will find a way to destroy you! You'll pay for the indignities you've heaped upon me...
I swear it! You're
dead, yes?"
"I... am...
not... your...
slave! I am your
executioner, yes?"
And his last words in the Marvel UK Transformers comics:
Rodimus Prime: "
What happened? Death's Head! Why did you pull me out?!"
Death's Head: "No time to explain. Go now -
Quickly!"
Rodimus Prime: "I don't understand. But I gather we all owe you a vote of thanks. Why the change of heart?"
Death's Head: "
Huh - No 'change of heart'. You're a
client, yes? Speaking of which, here come the two you paid me to
terminate - Cyclonus and Scourge! Go Prime - I'll finish business here, yes? What? No - The charges, they're
detonating! Time portal - Only chance! Kill you both another time, yes?
Literally!"
And one of his most classic lines of all:
"Stupid."

In all seriousness, I think the line to the destroyed Shockwave is his best one.