Fancy names
Amplitron Raytheon's  trademark name for a high power, crossed field microwave amplifier used in 1960's era RADAR
Anode The positive electrode.
Argon Inert gas used in some thyratrons
Augetron A kind of electron multiplicator.
Beam-X Switch Burroughs trademark name for their line of beam-switching counter tubes with internal magnets
Betatron Electron accelerator
Carcinotron A microwave oscillator tube (Backward-wave type) patented by Epsztain.
Cathode The negative electrode.
Cathovisor Television picture tube made by Baird Television 1939. (p.63, The CRT)
Catkin Metal tubes from Marconi
Cetron An old tube manufacturer
Chalnicon Camera tube produced by Hamamatsu. Features a high sensitivity over the range of visual spectrum. These tubes are typically more laggy than a Newvicon but provide higher resolution.
Charactron Computer readout CRT (p.77 The CRT)
You can find a picture and description of the 1698 HERE.
Chromatron A type of color TV picture tube developed by Ernest Lawrence 1951.
Citron Swedish name for lemon ;-)
Coketron An unusual CRT made of a Coca-Cola™ bottle (p.25 The CRT)
Compactron The last series of tubes from US makers. Equipped with a 12 pin base.
Control grid The grid closest to the cathode.
Corotron Gas discharge stabilizer tube made by Victoreen. Operated in the region 600-2000 volts. Also called Gas Corotron.
Cyclod A kind of CRT for pulse modulation.
Cyclophon Another kind of CRT for pulse demodulation.
Cyclotron Electron accelerator
Czicon Camera tube.
Dekatron L-M Ericsson's registered trade mark for decade counting tube, e.g. GC10/4B
Deltron An old tube manufacturer
Diode A tube with only two electrodes.
Dynatron A screen-grid tube in which secondary emission of electrons from the anode causes the anode current to decrease as anode voltage increases. This results in a negative resistance characteristic. Also known as Negatron.
Dynodes The name of the electrodes in a photomultiplier.
Eidophor A TV-projection system developed by Dr. F. Fischer from Switzerland. (p.150, The CRT) se also this site.
Eisen-Urdox An old type of NTC-resistor. These tubes were made by OSRAM and had a filament made of iron wire with a small resistor made of uranium dioxide on top of the system inside. (Thanks Burkhard Hasselmeier for the correct info)
Electron ...the smallest thing you can find in a tube.
Enneode Another name for Nonode, a tube with nine electrodes.
Escutcheon A thing that is used together with some decade counting tubes for indicating the displayed value..
Excitron A single-anode mercury pool tube that is designed to maintain a continuous cathode spot
Fetron Solid state tube (?)
Flatron Flat panel data displays from LG Electronic
Gammatron A gas discharge tube (TR-switch) type 6322 from Heinz & Kaufmann
Graphecon Storage CRT type 7539 made by RCA in 1949. More info here.
Gyrotron Microwave oscillator in the range of 82-118 GHz.
Haltron An old tube manufacturer
Healotron An instrument for healing infections by a stream of ozone ions
Heptode A tube with seven electrodes.
Hexode A tube with six electrodes.
Hivicon Camera tube.
Hydrogen Gas used in some thyratrons.
Hytron An old tube manufacturer
Iatron Electrostatic CRT with storage flood gun system. 7423
Iconoscope Camera tube
Ignitron Cold cathode rectifier.
More info HERE at Mike's Electric Stuff.
Image-Iconoscope An improved version of the Iconoscope
Image-Orthicon An improved version of the Orthicon
IOT Inductive Output Tube
Kenopliotron Kenopliotron contains a diode and a triode. The diode's anode is connected to the triode's cathode internally. Many thanks to Nusret Suzme for the translation from Turkish.
Kenotron A kenotron is a high-voltage rectifier
Kinescope Another name for TV picture tube
Klystron Microwave device
Krypton Inert gas
Krytron Krytrons are a highly specialized variety of cold cathode trigger tube
More info HERE at Mike's Electric Stuff
Lithocon A storage tube made by Princeton Electronic Products Inc in the 1970's.
Magnetron Microwave device
Megatron 1. An electron tube having disk-shaped electrodes arranged in closely spaced parallel layers, to give low interelectrode capacitance along with high power output, up to 2500 megahertz. Also known as lighthouse tube
2. Was also once upon a time a tube maker in The Netherlands (Hilversum)
MERB Multi Element Radial Beam Tube, used in sonar equipment during WWII. (Thanks Tom)
Milkotron A tube built into a milk bottle.
Minitron Another name for Numitron
Mnemotron An early version of a Dekatron
Monoscope Fixed pattern test picture generator, e.g. RCA 2F21
Monotron Another name for Monoscope
Negatron See Dynatron 
Neon Inert gas used in Nixie tubes. Welcome to Neon University
Neotron An old tube manufacturer
Neutron An elementary particle which has approximately the same mass as the proton but lacks electric charge
Nevitron A type of single-anode mercury-arc rectifier made by Nevidia Electric co
Newvicon Camera tube. Registered trademark of Matsushita. The tube was originally developed by Philips as an improved form of Vidicon. Newvicons are characterized by a high light sensitivity. The spectral response of the photoconductive target extends into the near infrared range.
Nixie Short for Numeric Indicator eXperimental
Nomotron A gasfilled decade counting tube made by STC (CVX2223/G10-241E), similar to a Dekatron,
Nonode A tube with nine electrodes, sometimes called Enneode.
NTSC National Televisions System Committee (aka Never The Same Color). Another interpretation is "Not Transmitted Sub Carrier", thanks Godfrey.
Nullode A tube without any electrodes, used as T/R switch in radar systems.
Numitron Display tube from RCA with seven filaments
Nuvistor A very small electron tube with metal envelope
Octode A tube with eight electrodes.
Omegatron Mass spectrometer tube Philips 56006.
Ophitron Registered trademark for an electrostatically focused backward wave oscillator from GEC M-O Valve, thanks John.
Orthicon Camera tube
Oscillite CRT made by Farnsworth ca 1930 (p.59 The CRT)
Oxytron Danish tube manufacturer
Ozotron Mike Harrison tells us:  It's a very sensitive device for detecting small amounts of halogen gases, consisting of 2 concentric cylinders, the inner one heated to 800 deg.C. When a high voltage is applied to the outer one, an increase in current will occur if there is any halogen gas (>1ppm) in the air between the cylinders. Made by EEV.
PAL Phase Alternate Line (aka Pay Another License), color TV system  developed by Dr Walter Burst, sorry I mean Bruch, at Telefunken.
Panaplex Burroughs cold-cathode neon display tube featuring eight or ten seven-segment digits
Pandicon Philips registered trade mark for a multiplexed display tube (ZM1200/02/04/06)
Pasecon Registered trademark of the Heimann division of EG&G. This is a highly sensitive camera tube with low dark current and excellent signal uniformity and resolution.
Penetron CRT with voltage-sensitive penetration phosphor (p.81 The CRT)
Pentode A tube with five electrodes.
Permatron Magnetically controlled mercury rectifier.
Phanotron Rectifier tube for HF currents
Phantasatron A strange tube presented by Eitel-McCullough on April, 1, 1950.
Phasitron A tube (2H21) for FM transmiters, more info here.
Phasmajector Another name for Monoscope
Photikon P.E.S-Photikon, an improved version of  the Image-Iconoscope
Pixie  A type of Nixie tube from Burroughs
Pliotron One type of triodes descibed by Irving Langmuir and Saul Dushman, together with Mr. William C. White. These tubes are exhausted to an exceedingly high vacuum by an elaborate process.
Plumbicon Philips registered trade mark for a camera tube. Target surface PbO.
Politron Some kind of tube made in Russia
Politron is an electronic-beam device with electrostatic control of beam of slow (non-reletavistic) electrones. Those electrones posses electron-mechanical dualism properties, ie simulteneously have properties of both electrical and mechanical particles of quantum mechanics domain. Initially device was created as electrically controlled non-linear or functional convertor of current or voltage in wide band of frequiencies from 0 to 30 MHz.  However, it appears during exploration, that the device has a phenomenal properties related to information conversion. Those properties still do not have strict mathematical description, but this does not limit practical usage of the device.
Positron An elementary particle with mass equal to that of the electron, and positive charge equal in magnitude to the electron's negative charge. 
Primicon The Primicon is a high quality medical grade tube developed by Thomson. Primicon tubes have high resolution and good lag characteristics.
Proton An elementary particle that is the positively charged constituent of ordinary matter and, together with the neutron, is a building block of all atomic nuclei 
Purotron Was a tube maker in the USA
Radechon The CRT 6499 from RCA is a Radechon. More info here.
Redifon Analog computer for radar display ?
Resistron The Resistron is a Vidicon type camera tube. It is suited for routine medical diagnostic procedures, since it provides high contrast with excellent resolution.
Resnatron A microwave-beam tetrode containing cavity resonators, used chiefly for generating large amounts of continuous power at high frequencies. More info HERE.
Saticon Camera tube, made by Heimann in Germany. Originally developed by Hitachi, this tube is licensed for manufacture by several firms, including Thomson and Heimann. The Saticon is a high quality, balanced tube providing high resolution and excellent contrast. It is slightly more laggy than a Plumbicon. It is well suited for the pick-up of quick moving images.
SECAM French color TV system
Selectron A binary memory tube from RCA.
Senditron A senditron is a quick acting switch able to carry currents up to several thousand amps.
Silicon A common chemical element abundant in ordinary sand, and the primary substance from which glass (as used in constructing the outer envelope of most vacuum tubes) is made.  
Skiatron Dark trace storage tube made by RCA in 1944 (p.76 The CRT)
Spectracon Some kind of Image Tube, more info here.
Sprytron Otherwise known as the Vacuum Krytron
More info HERE at Mike's Electric Stuff
Strobotron A gas-filled cathode-ray tube that produces bright flashes of light for a stroboscope.
Synchrotron Electron accelerator
Teleion Gas discharge relay valve, thanks John.
Tetrode A tube with four electrodes
Tfk Short for Telefunken
Thyratron Electronic switch usually a gas filled triode or tetrode
More info HERE at Mike's Electric Stuff
Thyrode Geiger-Müller type counting tube 6306 made by Victoreen.
Tonotron Direct view CRT for storage of halftone images, Hughes Aircraft 1956 (a picture can be found on p.79 The CRT)
Transitron Circuit whose action depends on the negative transconductance of the suppressor grid of a pentode with respect to the screen grid.
Trigatron  A kind of thyratron. More info HERE at Mike's Electric Stuff
Triode A tube with three electrodes
Trinicon Sony registered trade mark for a Color TV camera tube. Here is a description of the Sony DXC-1600 one tube color camera.
Trinitron Sony registered trade mark for a Color TV picture tube developed 1968.
Trinoscope CRT for a color-TV system developed by RCA 1946 (p. 172 The CRT)
Triotron An old tube maker.
Trochotron A (beam switching) electron tube in which a magnetic field causes the electrons to travel in trochoidal paths. Used in decade counter tube from LME.
Tunoscope Tungsram's name on their "magic eye" ME4
Typotron A Charactron with a storage tube screen structure (p. 197 The CRT)
Ultor Another name for the final accelerator electrode in a CRT.
Ultron An old tube manufacturer
Utilicon Image Dissector, a rare type of imaging tube.
Vacuum What most electron tubes are filled with more or less ;-)
Vapotron  An innovative anode cooled by water vaporization, developed by Charles Beurtheret of Thomson-Houston in 1950.
Velocitron A Klystron from Klystronics Inc.
Vidicon Camera tube, target surface Sb2S3
Wamoscope Sylvania Travelling Wave Amplifier CRT, see The CRT, page 81.
Xenon Inert gas used in some thyratrons

Do you know any more fancy names ?
Your contribution to this page is most welcome.