"Inspector Gadget" The Infiltration (TV Episode 1983) - Frank Welker as Prest-O Change-O

Dr. Claw : So, you're the great Prest-O Change-O, the human chameleon.

Prest-O Change-O : [chuckles] At your service.
[Gadget enters the conference room to discover that Prest-O Change-O disguised as Gadget is already there. Chief Quimby looks and points at who he thought was Gadget in shock. Then, Gadget and Prest-O Change-O get into a stand-off]

Inspector Gadget , Prest-O Change-O : [simultaneously] Arrest him, Chief! That's Prest-O Change-O! I am not! You are so!
Dr. Claw : Our mutual friend Inspector Gadget will be unable to attend the police security conference this year.

Prest-O Change-O : Oh?

Dr. Claw : Unfortunately, he met with an untimely death in a boating accident.

Prest-O Change-O : [chuckles] And you want me to disguise myself as Gadget, and take his place?

Dr. Claw : Correct. You see, every year at this conference, top secret plans are discussed. Plans to stop me! From doing what I do best! Of course, if I knew their plans in advance - heh - I really don't see how they'd have a chance against me.

[Claw and Presto laugh]
[after Presto, disguised as Gadget, tells the security guard that Penny is Prest-O Change-O, the guard then cuffs Penny]

Penny : [to the security guard] Wait! You're making a big mistake! I'm Inspector Gadget's niece, and he's not Gadget!

Prest-O Change-O : [using Gadget's voice] Impeccable research. I actually do have a niece.

Security Guard : [to Penny] Okay, Miss Change-O, let's go!

[Presto then discreetly laughs it off]

Frank Welker: Prest-O Change-O