The weird robot from Mighty Morphin' Power Rangers.
Alpha liked to hang out with Zordon in the Power Chamber, frequently furrowing his robot-brow, waving his arms wildly and shouting "Aye-aye-aye! The Rangers are in trouble!" As far as I could tell, the only reason he was useful was cause Zordon didn't have hands to do things himself.
Alpha Five was the first incarnation we actually saw on the series. At some point (perhaps during Power Rangers Turbo) he was replaced by Alpha Six, who for some reason liked to rap. Such phrases as "Yo yo, wasup, Powa Range's?" were frequently heard coming from his mouth. Of course, there have been about twelve Power Rangers series since then. Zordon (that's the big head in the tube) is long since dead - believe it or not, his death supposedly killed all the bad guys in the galaxy. Apparently that's why they have to go to a new galaxy and change the name of the show every week now. Sounds like bad planning to me. Presumably, with Zordon gone, Alpha committed suicide, or got a real job, or something.
Yes, it is scary that I know this information.