No agency dominates its home market as wholly as Dentsu, which controls around 30% of Japan's mass media advertising. But while it has established a strong presence in other Asian territories, the Dentsu brand has little profile in Western markets, compared to sister network McGarryBowen

DDB's principal founder Bill Bernbach is often considered to be the single most influential figure in post-war advertising. Now a subsidiary of Omnicom, DDB Group also houses a collection of other agencies including CRM network Rapp, branding agency Interbrand and digital specialist Tribal.

BBDO is arguably the world's most admired creative network, having won more industry awards since 2005 than any other. The main advertising agency is the biggest by revenues in the US, and regional units such as AMV BBDO of the UK and Clemenger BBDO of Australia lead their own local markets.

Hakuhodo is Japan's second largest ad agency behind Dentsu, but has an even less widespread international presence, with only a handful of low key subsidiaries outside its domestic market. Its parent company also owns two other major local agencies, Daiko and Yomiko.

TBWA is the youngest of the three advertising networks within Omnicom, positioned as an alternative brand, with a reputation for "disruptive" work. It is best known for its work for keystone clients such as Nissan and especially Apple, for whom it has created a series of iconic marketing campaigns.

One of the pioneers in global marketing, McCann Erickson was the first ad agency to diversify into other marketing disciplines. McCann Worldgroup also contains PR giant Weber Shandwick, and branding specialist Futurebrand as well as healthcare, sales promotion and CRM specialists.

David Ogilvy created Ogilvy & Mather virtually from scratch in the years after WW2, establishing himself as one of the ad industry's most influential figures. The agency remains a global powerhouse, with skills across the whole range of marketing disciplines including healthcare, PR and CRM.

Wunderman Thompson was created in 2018 from the merger of WPP's long-established but poorly performing J Walter Thompson with fast-growing digital and direct sibling Wunderman. For the most part, Wunderman's management team has gained the upper hand in the combined entity.

The only global network still headquartered in France, Publicis is the biggest brand within the group of the same name, sitting alongside acquired businesses such Leo Burnett and Saatchi. Despite a global presence, the main Publicis Conseil office in Paris remains the network's clear flagship.

Traditionally the smallest of the four major networks within WPP, Grey moved up the ranks as a result of strong and stready growth. Creative output has improved drama-tically in recent years, but Grey is best-known for diligent account management and long-lasting client relationships.

Havas (known as Euro RSCG until 2014) is the main advertising network within the French marketing group of the same name. The last of the major independent agency networks until 2016, it is now a unit of French media and telecoms group Vivendi.

Now one of three major advertising networks within Publicis Groupe, Leo Burnett pioneered what used to be called the "Chicago school" of advertising, which personalises client brands' core values in the form of a brand mascot: such as Uncle Ben, the Marlboro man or the Jolly Green Giant.

A unit of WPP since 2000, Y&R was until 2018 the main ad network within the wider Young & Rubicam group, alonside Wunderman and other agencies. In 2018, WPP announced Y&R's separation from Wunderman and its merger instead with digital agency VML to form VMLY&R

FCB readopted its old name in 2014 after several years as Draftfcb. That entity was created from the merger of the old Foote Cone & Belding agency with direct marketer Draft, also owned by Interpublic, to create an integrated worldwide marketing services giant.

South Korea's biggest ad agency has established a global network to support key client and part-owner Samsung, proving that "inhouse" agencies can be just as dynamic as traditional third-party ones. Its skillset has been boosted by acquisitions including global network Iris and BMB in the UK.

Serviceplan is Germany's biggest independent advertising and marketing group, and has gradually established an extensive presence across several other European markets and more recently into Asia and North America as well. It is privately owned and run by the Haller family.

In its heyday in the 1980s, Saatchi & Saatchi was the world's biggest ad company, before falling upon hard times. Owned by Publicis Groupe since 2000, it's somewhat smaller now, but still the world's most famous advertising brand; the only one recognised by members of the ordinary public.

MullenLowe was created in 2015 from merger of Interpublic's creatively admired Lowe & Partners with the standalone US agency Mullen. It is the latest of several attempts to establish a lasting presence for Lowe in the US, following earlier alliances with Deutsch and Campbell Ewald.

Wieden & Kennedy is a fierce challenger for the crown of World's Most Admired Agency. Already the coolest shop in the business, it has an unrivalled reputation for memorable advertising. Not just for cornerstone client Nike, but also for the likes of Old Spice, and until recently Chrysler and Heineken.

M&C is the other global ad agency created by Maurice & Charles Saatchi, after they were ousted from their original business. In many markets, it actually overshadows the older network, and also manages its own small collection of diversified specialist subsidiaries.

Droga5 is another rival for the title of World's Most Admired Agency. It was founded by former Publicis creative leader David Droga, still its chairman and main guiding presence. In a shock development in 2019 it became the biggest addition to-date to Accenture's advertising portfolio.

New York agency McGarryBowen was the most ambitious of Dentsu's Western acquisitions in the 2000s. It has absorbed and rejuvenated the Japanese group's Dentsu-branded outposts in other countries, establishing a significant presence as a global advertising brand in its own right.

Forsman & Bodenfors is the newly renamed lead agency within challenger marketing group MDC Partners. It was formed in 2018 from the merger and surprise rebranding of US-based KBS with Swedish creative hothouse Forsman & Bodenfors.

Bartle Bogle Hegarty (or BBH) has long ranked as one of the world's most admired creative agencies, with a reputation for stylish, elegant and original advertising. Despite the departure of its founding partners following a full buyout by Publicis Groupe, it has retained its style and strength.