The List
There are 621 5 letter words with G as the first letter. The highest scoring is GYOZA at 18 points in Scrabble, though Words With Friends prefers GAUZY at 20. 9 of them contain no vowel at all: GHYLL, GLYPH, GRRLS, GRRRL, GRYPT, GYMPS, among others.
GABBAGABBYGABLEGADDIGADESGADGEGADIDGADISGADJEGADJOGADSOGAFFEGAFFSGAGEDGAGERGAGESGAIDSGAILYGAINSGAIRSGAITAGAITSGAITTGAJOSGALAHGALASGALAXGALEAGALESGALLSGALLYGALOPGALUTGALVOGAMASGAMAYGAMBAGAMBEGAMBOGAMBSGAMEDGAMERGAMESGAMEYGAMICGAMINGAMMAGAMMEGAMMYGAMPSGAMUTGANCHGANDYGANEFGANEVGANGSGANJAGANOFGANTSGAOLSGAPEDGAPERGAPESGAPOSGAPPYGARBEGARBOGARBSGARDAGARISGARNIGARREGARTHGARUMGASESGASPSGASPYGASSYGASTSGATEDGATERGATESGATHSGATORGAUCYGAUDSGAUDYGAUGEGAUJEGAULTGAUMSGAUMYGAUNTGAUPSGAURSGAUSSGAUZEGAUZYGAVELGAVOTGAWCYGAWDSGAWKSGAWKYGAWPSGAWSYGAYALGAYERGAYLYGAZALGAZARGAZEDGAZERGAZESGAZONGAZOOGEALSGEANSGEAREGEARSGEATSGEBURGECKOGECKSGEEKSGEEKYGEEPSGEESEGEESTGEISTGEITSGELDSGELEEGELIDGELLYGELTSGEMELGEMMAGEMMYGEMOTGENALGENASGENESGENETGENICGENIEGENIIGENIPGENNYGENOAGENOMGENREGENROGENTSGENTYGENUAGENUSGEODEGEOIDGERAHGERBEGERESGERLEGERMSGERMYGERNEGESSEGESSOGESTEGESTSGETASGETUPGEUMSGEYANGEYERGHASTGHATSGHAUTGHAZIGHEESGHESTGHOSTGHOULGHYLLGIANTGIBEDGIBELGIBERGIBESGIBLIGIBUSGIDDYGIFTSGIGASGIGHEGIGOTGIGUEGILASGILDSGILETGILLSGILLYGILPYGILTSGIMELGIMMEGIMPSGIMPYGINGEGINGSGINKSGINNYGINZOGIPONGIPPOGIPPYGIPSYGIRDSGIRLSGIRLYGIRNSGIRONGIROSGIRRSGIRSHGIRTHGIRTSGISMOGISMSGISTSGITESGIUSTGIVEDGIVENGIVERGIVESGIZMOGLACEGLADEGLADSGLADYGLAIKGLAIRGLAMSGLANDGLANSGLAREGLARYGLASSGLAUMGLAURGLAZEGLAZYGLEAMGLEANGLEBAGLEBEGLEBYGLEDEGLEDSGLEEDGLEEKGLEESGLEETGLEISGLENSGLENTGLEYSGLIALGLIASGLIBSGLIDEGLIFFGLIFTGLIKEGLIMEGLIMSGLINTGLISKGLITSGLITZGLOAMGLOATGLOBEGLOBIGLOBSGLOBYGLODEGLOGGGLOMSGLOOMGLOOPGLOPSGLORYGLOSSGLOSTGLOUTGLOVEGLOWSGLOZEGLUEDGLUERGLUESGLUEYGLUGSGLUMEGLUMSGLUONGLUTEGLUTSGLYPHGNARLGNARRGNARSGNASHGNATSGNAWNGNAWSGNOMEGNOWSGOADSGOAFSGOALSGOARYGOATSGOATYGOBANGOBARGOBBIGOBBOGOBBYGOBISGOBOSGODETGODLYGODSOGOELSGOERSGOESTGOETHGOETYGOFERGOFFSGOGGAGOGOSGOIERGOINGGOJISGOLDSGOLDYGOLEMGOLESGOLFSGOLLYGOLPEGOLPSGOMBOGOMERGOMPAGONADGONEFGONERGONGSGONIAGONIFGONKSGONNAGONOFGONYSGONZOGOOBYGOODSGOODYGOOEYGOOFSGOOFYGOOGSGOOKSGOOKYGOOLDGOOLSGOOLYGOONSGOONYGOOPSGOOPYGOORSGOORYGOOSEGOOSYGOPAKGOPIKGORALGORASGOREDGORESGORGEGORISGORMSGORMYGORPSGORSEGORSYGOSHTGOSSEGOTHSGOTTAGOUCHGOUGEGOUKSGOURAGOURDGOUTSGOUTYGOWANGOWDSGOWFSGOWKSGOWLSGOWNSGOXESGOYIMGOYLEGRAALGRABSGRACEGRADEGRADSGRAFFGRAFTGRAILGRAINGRAIPGRAMAGRAMEGRAMPGRAMSGRANAGRANDGRANSGRANTGRAPEGRAPHGRAPYGRASPGRASSGRATEGRAVEGRAVSGRAVYGRAYSGRAZEGREATGREBEGREBOGRECEGREEDGREEKGREENGREESGREETGREGEGREGOGREINGRENSGRESEGREVEGREWSGREYSGRICEGRIDEGRIDSGRIEFGRIFFGRIFTGRIGSGRIKEGRILLGRIMEGRIMYGRINDGRINSGRIOTGRIPEGRIPSGRIPTGRIPYGRISEGRISTGRISYGRITHGRITSGRIZEGROANGROATGRODYGROGSGROINGROKSGROMAGRONEGROOFGROOMGROSSGROSZGROTSGROUFGROUPGROUTGROVEGROWLGROWNGROWSGRRLSGRRRLGRUBSGRUEDGRUELGRUESGRUFEGRUFFGRUMEGRUMPGRUNDGRUNTGRYCEGRYDEGRYKEGRYPEGRYPTGUACOGUANAGUANOGUANSGUARDGUARSGUAVAGUCKSGUCKYGUDESGUESSGUESTGUFFSGUGASGUIDEGUIDSGUILDGUILEGUILTGUIMPGUIROGUISEGULAGGULARGULASGULCHGULESGULETGULFSGULFYGULLSGULLYGULPHGULPSGULPYGUMBOGUMMAGUMMYGUMPSGUNDYGUNGEGUNGYGUNKSGUNKYGUNNYGUPPYGUQINGURGEGURLSGURLYGURNSGURRYGURSHGURUSGUSHYGUSLAGUSLEGUSLIGUSSYGUSTOGUSTSGUSTYGUTSYGUTTAGUTTYGUYEDGUYLEGUYOTGUYSEGWINEGYALSGYBEDGYBESGYELDGYMPSGYNAEGYNIEGYNNYGYOZAGYPPOGYPPYGYPSYGYRALGYREDGYRESGYRONGYROSGYRUSGYTESGYVEDGYVES