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5.
Leader of the deceptacons. The guy who mortally wounded Optimus, losing his identity to Unicron as an indirect result.
"As you should know by now, Megatron is very hard to kill," -Megatron
by AdmiralDavidov August 06, 2005
 
1.
Leader of the Decepticon Transformers. Transforms into a Walther pistol, but rarely actually does so in the TV series on account of this being a particularly useless thing to transform into. A psychotic, maniacal genius, Megatron is pure of evil and huge of gun.
"Megatron: sort of like Darth Vader, but simultaneously not."
by Popcorn December 01, 2003
 
2.
Megatron is a Canadian trademark of Megatron Communications inc. Montreal Quebec Canada.
Since 1989, Megatron is sending fax broadcast in Canada, USA, Australia, Europe, China, Hong Kong, etc.
Megatron Fax Broadcast
Megatron Communications inc.
Megatron Net
Megatron Emailling
Megatron Faxing
Megatron Faxbroadcasting
Service Megatron
by Megatron Communications inc. December 04, 2011
 
3.
1. Leader of the decepticons

2. Deadliest NFL wide Calvin Johnson
1. "There goes Megatron terrorizing cities, and fighting optimus prime."

2. "Megatron with the 60 yard reception!"
by Ricky Tang July 06, 2014
 
4.
Evil leader of the Decepticons. His goal is to rule the universe and destroy everyone in his path....even one of his warriors.
Join me and I shall send you into battle, Defy me and I shall send you to oblivion!!--Megatron (from transformers Energon) quote
by Aimee January 10, 2005
 
6.
1.(Pronoun) Vile, Despicable leader of the Decepticon Army during the first 2 seasons of the G1 Transformers series during the 80's. Came up with many plots and schemes that were often foiled by the Autobots. The only time he came closest to victory was during the last episode of Season 1..Heavy Metal War.
Shockwave: Laserbeak returns Megatron..
Megatron: Welcome Laserbeak! Unlike some of my other warriors, you never fail me!
by El Diablocron December 23, 2005
 
7.
A penis that exhibits the "grower" characteristic of significantly expanding and lengthening upon erection as opposed to the "shower" characteristic where it is already near maximum size at rest and does not get much bigger upon erection.
Hey, baby. How you doing? Don't be fooled by the Decepticon in my pants. My Megatron is full of destructive force capable of making you/your Starscream.
by BaboonKiller December 08, 2013